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SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - AOCI (Details) - USD ($) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016
Accumulated other comprehensive income (loss) |  |  |
Beginning Balance | $ 688,727 |  |
Adjust funded status of pension plan, net of tax of $0.6, $0.7 and $0.7 million for the years December 31, 2018, 2017 and 2016 respectively | (840) | $ 1,357 | $ 5,251
Foreign currency translation adjustment | (4,390) | 1,265 | (687)
Reclassifications of gains on sale of marketable securities to net income |  | (1,044) |
Unrealized gain on marketable securities | 78 | 440 | 868
Ending Balance | 695,387 | 688,727 |
Adjust funded status of pension plan, tax | 600 | 700 | 700
Accumulated Other Comprehensive Income/(Loss) |  |  |
Accumulated other comprehensive income (loss) |  |  |
Beginning Balance | 3,746 | 1,728 | (3,704)
Adjust funded status of pension plan, net of tax of $0.6, $0.7 and $0.7 million for the years December 31, 2018, 2017 and 2016 respectively | (840) | 1,357 | 5,251
Foreign currency translation adjustment | (4,390) | 1,265 | (687)
Reclassifications of gains on sale of marketable securities to net income | (203) | (1,044) |
Unrealized gain on marketable securities | 78 | 440 | 868
Ending Balance | (1,609) | 3,746 | 1,728
Pension and other postretirement benefit plans |  |  |
Accumulated other comprehensive income (loss) |  |  |
Beginning Balance | 3,127 | 1,770 | (3,481)
Adjust funded status of pension plan, net of tax of $0.6, $0.7 and $0.7 million for the years December 31, 2018, 2017 and 2016 respectively | (840) | 1,357 | 5,251
Ending Balance | 2,287 | 3,127 | 1,770
Translation Adjustment |  |  |
Accumulated other comprehensive income (loss) |  |  |
Beginning Balance | 355 | (910) | (223)
Foreign currency translation adjustment | (4,390) | 1,265 | (687)
Ending Balance | (4,035) | 355 | (910)
Investment |  |  |
Accumulated other comprehensive income (loss) |  |  |
Beginning Balance | 264 | 868 |
Reclassifications of gains on sale of marketable securities to net income | (203) | (1,044) |
Unrealized gain on marketable securities | 78 | 440 | 868
Ending Balance | $ 139 | $ 264 | $ 868

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