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Summary Of Significant Accounting Policies (Narrative) (Details). - USD ($) $ in Thousands | 3 Months Ended | 12 Months Ended |
--- | --- | --- | ---
Dec. 31, 2018 | Sep. 30, 2018 | Jun. 30, 2018 | Dec. 31, 2017 | Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
Summary Of Significant Accounting Policies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Effect of Adoption on Share-Based Compensation |  |  |  |  |  |  |  |  | $ 1,100 |  |  |
Foreign Income Tax Expense (Benefit), Continuing Operations |  |  |  |  |  |  | $ 13,300 |  |  |  |  |
Interest Costs Capitalized |  |  |  |  |  |  | 300 |  | 400 |  | $ 300 |
Foreign Currency Transaction Gain (Loss), before Tax |  |  |  |  |  |  | 500 |  | 800 |  | 3,600 |
Cash and cash equivalents | $ 34,397 | [1] |  |  | $ 36,491 | [1] | $ 34,397 | [1] | 36,491 | [1] | 29,511 | $ 44,156
Investments, percentage of voting ownership interest | 50.00% |  |  |  |  |  | 50.00% |  |  |  |  |
Goodwill, Impairment Loss |  |  |  |  |  |  | $ 46,792 |  | 0 |  | 0 |
Goodwill | $ 81,404 |  |  |  | 128,208 |  | $ 81,404 |  | $ 128,208 |  | $ 117,822 |
Incremental shares excluded from the calculation of incremental shares attributable to stock options and restricted stock |  |  |  |  |  |  | 128,200 |  | 397,669 |  | 726,475 |
Asset Impairment Charges |  |  |  |  |  |  | $ 223 |  | $ 101,282 |  | $ 1,436 |
Foreign Country |  |  |  |  |  |  |  |  |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Cash and cash equivalents | 31,100 |  |  |  | 32,700 |  | $ 31,100 |  | 32,700 |  |  |
Minimum | Buildings And Land Improvements |  |  |  |  |  |  |  |  |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Average useful life |  |  |  |  |  |  | 5 years |  |  |  |  |
Minimum | Machinery and Equipment |  |  |  |  |  |  |  |  |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Average useful life |  |  |  |  |  |  | 2 years |  |  |  |  |
Maximum | Buildings And Land Improvements |  |  |  |  |  |  |  |  |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Average useful life |  |  |  |  |  |  | 40 years |  |  |  |  |
Maximum | Machinery and Equipment |  |  |  |  |  |  |  |  |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Average useful life |  |  |  |  |  |  | 20 years |  |  |  |  |
Aluminum Extrusions |  |  |  |  |  |  |  |  |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Goodwill, Impairment Loss |  |  |  |  |  |  | $ 0 |  |  |  |  |
Goodwill | 24,066 |  |  |  | 24,066 |  | 24,066 |  | 24,066 |  | 13,696 |
PE Films [Member] |  |  |  |  |  |  |  |  |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Goodwill, Impairment Loss |  |  |  |  |  |  | (46,800) |  | 0 |  | $ 0 |
Goodwill, Impairment Loss, Net of Tax |  |  | $ 38,200 |  |  |  | 38,200 |  |  |  |  |
Flexible Packaging Films [Member] |  |  |  |  |  |  |  |  |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Assets, Fair Value Disclosure | 30,000 |  |  |  | 30,000 |  | 30,000 |  | 30,000 |  |  |
Foreign Income Tax Expense (Benefit), Continuing Operations |  |  |  | $ 400 |  |  |  |  |  |  |  |
Asset Impairment Charges | 101,000 |  |  |  | 101,000 |  | 101,000 |  | 101,000 |  |  |
Asset Impairment Charges After Taxes |  |  |  |  | $ 87,000 |  | $ 87,000 |  | $ 87,000 |  |  |
Customer Relationships [Member] | Minimum |  |  |  |  |  |  |  |  |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Finite-Lived Intangible Asset, Useful Life |  |  |  |  |  |  | 10 years |  |  |  |  |
Customer Relationships [Member] | Maximum |  |  |  |  |  |  |  |  |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Finite-Lived Intangible Asset, Useful Life |  |  |  |  |  |  | 12 years |  |  |  |  |
Customer Relationships [Member] | Flexible Packaging Films [Member] | Minimum |  |  |  |  |  |  |  |  |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Finite-Lived Intangible Asset, Useful Life |  |  |  |  |  |  | 5 years |  | 5 years |  |  |
Customer Relationships [Member] | Flexible Packaging Films [Member] | Maximum |  |  |  |  |  |  |  |  |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Finite-Lived Intangible Asset, Useful Life |  |  |  |  |  |  | 13 years |  | 13 years |  |  |
Other Intangible Assets [Member] | Flexible Packaging Films [Member] |  |  |  |  |  |  |  |  |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Impairment of Intangible Assets, Indefinite-lived (Excluding Goodwill) |  |  |  |  |  |  | $ 14,000 |  |  |  |  |
Trade Names [Member] | Minimum |  |  |  |  |  |  |  |  |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Finite-Lived Intangible Asset, Useful Life |  |  |  |  |  |  | 2 years |  |  |  |  |
Trade Names [Member] | Maximum |  |  |  |  |  |  |  |  |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Finite-Lived Intangible Asset, Useful Life |  |  |  |  |  |  | 12 years |  |  |  |  |
Trade Names [Member] | Flexible Packaging Films [Member] |  |  |  |  |  |  |  |  |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Finite-Lived Trade Names, Gross | 2,400 |  |  |  |  |  | $ 2,400 |  |  |  |  |
Trade Names [Member] | Flexible Packaging Films [Member] |  |  |  |  |  |  |  |  |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Impairment of Intangible Assets, Indefinite-lived (Excluding Goodwill) |  |  |  |  |  |  | 4,000 |  |  |  |  |
Goodwill [Member] | Futura [Member] |  |  |  |  |  |  |  |  |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Goodwill | 10,400 |  |  |  |  |  | 10,400 |  |  |  |  |
Goodwill [Member] | Aacoa [Member] |  |  |  |  |  |  |  |  |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Goodwill | 13,700 |  |  |  |  |  | 13,700 |  |  |  |  |
Goodwill [Member] | Surface protection films |  |  |  |  |  |  |  |  |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Goodwill | $ 57,300 |  |  |  |  |  | $ 57,300 |  |  |  |  |
[1] | Information on exports and foreign operations are provided on the previous page. Cash and cash equivalents includes funds held in locations outside the U.S. of $31.1 million and $32.7 million at December 31, 2018 and 2017, respectively. Export sales relate almost entirely to PE Films. Operations outside the U.S. in The Netherlands, Hungary, China and India also relate to PE Films. Operations in Brazil are primarily related to Flexible Packaging Films, but also include PE Films operations. Sales from locations in The Netherlands and Hungary are primarily to customers located in Europe. Sales from locations in China (Guangzhou and Shanghai) are primarily to customers located in China, but also include other customers in Asia.

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