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Accumulated Other Comprehensive (Loss) Income (Details) - USD ($) $ in Thousands | 3 Months Ended | 9 Months Ended |  |
--- | --- | --- | --- | ---
Sep. 30, 2018 | Jun. 30, 2018 | Mar. 31, 2018 | Sep. 30, 2017 | Jun. 30, 2017 | Mar. 31, 2017 | Sep. 30, 2018 | Sep. 30, 2017 | Dec. 31, 2017 | Dec. 31, 2016
AOCI Attributable to Parent, Net of Tax [Roll Forward] |  |  |  |  |  |  |  |  |  |
AOCI before tax, beginning balance | $ (7,289) | $ (5,539) | $ (5,336) | $ (6,945) | $ (8,079) | $ (8,801) | $ (5,336) | $ (8,801) |  |
Accumulated other comprehensive income, tax, beginning balance | (949) | (960) | (970) | (1,047) | (1,063) | (1,080) | (970) | (1,080) |  |
Accumulated Other Comprehensive Income Beginning Balance | (6,340) | (4,579) | (4,366) | (5,898) | (7,016) | (7,721) | (4,366) | (7,721) |  |
Cumulative effect of new accounting principle in period of adoption |  |  |  |  |  |  |  |  | $ 274 | $ 0
Other comprehensive income (loss), net of tax | 166 |  |  | 1,608 |  |  | (1,808) | 3,431 |  |
AOCI before tax, ending balance | (7,113) | (7,289) | (5,539) | (5,321) | (6,945) | (8,079) | (7,113) | (5,321) |  |
Accumulated other comprehensive income, tax, ending balance | (939) | (949) | (960) | (1,031) | (1,047) | (1,063) | (939) | (1,031) |  |
Accumulated Other Comprehensive Income Ending Balance | (6,174) | (6,340) | (4,579) | (4,290) | (5,898) | (7,016) | (6,174) | (4,290) |  |
Accumulated Translation Adjustment |  |  |  |  |  |  |  |  |  |
AOCI Attributable to Parent, Net of Tax [Roll Forward] |  |  |  |  |  |  |  |  |  |
AOCI before tax, beginning balance | (4,375) | (2,588) | (2,698) | (4,078) | (5,169) | (5,848) | (2,698) | (5,848) |  |
Other comprehensive income adjustments | 139 | (1,787) | 110 | 1,581 | 1,091 | 679 |  |  |  |
Other comprehensive income (loss), net of tax | 139 | (1,787) | 110 | 1,581 | 1,091 | 679 |  |  |  |
AOCI before tax, ending balance | (4,236) | (4,375) | (2,588) | (2,497) | (4,078) | (5,169) | (4,236) | (2,497) |  |
Accumulated Defined Benefit Plans Adjustment |  |  |  |  |  |  |  |  |  |
AOCI Attributable to Parent, Net of Tax [Roll Forward] |  |  |  |  |  |  |  |  |  |
Other comprehensive income adjustments | 37 | 37 | 37 | 43 | 43 | 43 |  |  |  |
Other comprehensive income (loss), tax | 10 | 11 | 10 | 16 | 16 | 17 |  |  |  |
Other comprehensive income (loss), net of tax | 27 | 26 | 27 | 27 | 27 | 26 |  |  |  |
Accumulated Other Comprehensive Loss |  |  |  |  |  |  |  |  |  |
AOCI Attributable to Parent, Net of Tax [Roll Forward] |  |  |  |  |  |  |  |  |  |
Cumulative effect of new accounting principle in period of adoption |  |  |  |  |  |  |  |  | (350) | $ 0
Minimum Pension Liability Adjustment | Accumulated Defined Benefit Plans Adjustment |  |  |  |  |  |  |  |  |  |
AOCI Attributable to Parent, Net of Tax [Roll Forward] |  |  |  |  |  |  |  |  |  |
AOCI before tax, beginning balance | 172 | 179 | 171 | 188 | 192 | 197 | 171 | 197 |  |
Other comprehensive income adjustments | (7) | (7) | (7) | (4) | (4) | (5) |  |  |  |
AOCI before tax, ending balance | 165 | 172 | 179 | 184 | 188 | 192 | 165 | 184 |  |
Postretirement Health Coverage | Accumulated Defined Benefit Plans Adjustment |  |  |  |  |  |  |  |  |  |
AOCI Attributable to Parent, Net of Tax [Roll Forward] |  |  |  |  |  |  |  |  |  |
AOCI before tax, beginning balance | (3,086) | (3,130) | (2,809) | (3,055) | (3,102) | (3,150) | (2,809) | (3,150) |  |
Other comprehensive income adjustments | 44 | 44 | 44 | 47 | 47 | 48 |  |  |  |
AOCI before tax, ending balance | $ (3,042) | $ (3,086) | $ (3,130) | $ (3,008) | $ (3,055) | $ (3,102) | $ (3,042) | $ (3,008) |  |
Accounting Standards Update 2014-09 |  |  |  |  |  |  |  |  |  |
AOCI Attributable to Parent, Net of Tax [Roll Forward] |  |  |  |  |  |  |  |  |  |
Cumulative effect of new accounting principle in period of adoption |  |  |  |  |  |  |  |  | (350) |
Accounting Standards Update 2014-09 | Accumulated Other Comprehensive Loss |  |  |  |  |  |  |  |  |  |
AOCI Attributable to Parent, Net of Tax [Roll Forward] |  |  |  |  |  |  |  |  |  |
Cumulative effect of new accounting principle in period of adoption |  |  |  |  |  |  |  |  | (350) |
Accounting Standards Update 2014-09 | Minimum Pension Liability Adjustment | Accumulated Defined Benefit Plans Adjustment |  |  |  |  |  |  |  |  |  |
AOCI Attributable to Parent, Net of Tax [Roll Forward] |  |  |  |  |  |  |  |  |  |
Cumulative effect of new accounting principle in period of adoption |  |  |  |  |  |  |  |  | 15 |
Accounting Standards Update 2014-09 | Postretirement Health Coverage | Accumulated Defined Benefit Plans Adjustment |  |  |  |  |  |  |  |  |  |
AOCI Attributable to Parent, Net of Tax [Roll Forward] |  |  |  |  |  |  |  |  |  |
Cumulative effect of new accounting principle in period of adoption |  |  |  |  |  |  |  |  | $ (365) |

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