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Investments (Narrative) (Details) - USD ($) $ in Thousands |  | 3 Months Ended | 12 Months Ended |
--- | --- | --- | --- | ---
Apr. 02, 2007 | Dec. 31, 2016 | Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015 | Dec. 31, 2008
Investments, Other Investments [Line Items] |  |  |  |  |  |  |  |  |
Gain (loss) on investment accounted for under the fair value method |  |  | $ (33,800) |  | $ (1,600) |  | $ 20,500 |  |
kaleo |  |  |  |  |  |  |  |  |
Investments, Other Investments [Line Items] |  |  |  |  |  |  |  |  |
Total cash invested in private company |  |  |  |  |  |  |  |  | $ 7,500
Ownership interest percentage |  |  | 20.00% |  |  |  |  |  |
Gain (loss) on investment accounted for under the fair value method |  | $ (1,600) | $ (33,800) | [1] | $ (1,600) | [1] | 20,500 | [1] |
Unrealized gain (loss) on investments, net of tax |  | $ 1,200 | $ 24,000 |  |  |  | (15,700) |  |
Weighted average cost of capital |  | 45.00% | 45.00% |  | 45.00% |  |  |  |
Basis point decrease of weighted average cost of capital assumption |  |  | 5.00% |  |  |  |  |  |
Increase in fair value from five hundred point decrease in weighted average cost of capital assumption |  |  | $ 11,000 |  |  |  |  |  |
Basis point increase of weighted average cost of capital assumption |  |  | 5.00% |  |  |  |  |  |
Decrease in fair value from five hundred point increase in weighted average cost of capital assumption |  |  | $ 10,000 |  |  |  |  |  |
Harbinger |  |  |  |  |  |  |  |  |
Investments, Other Investments [Line Items] |  |  |  |  |  |  |  |  |
Total cash invested in private company | $ 10,000 |  |  |  |  |  |  |  |
Withdrawal proceeds |  |  | 0 |  |  |  | 100 |  |
Maximum | Harbinger |  |  |  |  |  |  |  |  |
Investments, Other Investments [Line Items] |  |  |  |  |  |  |  |  |
Percent ownership in investment (less than) | 1.00% |  |  |  |  |  |  |  |
Other Assets and Deferred Charges [Member] | kaleo |  |  |  |  |  |  |  |  |
Investments, Other Investments [Line Items] |  |  |  |  |  |  |  |  |
Carrying value |  | $ 20,200 | 54,000 |  | $ 20,200 |  |  |  |
Other Assets and Deferred Charges [Member] | Harbinger |  |  |  |  |  |  |  |  |
Investments, Other Investments [Line Items] |  |  |  |  |  |  |  |  |
Carrying value of investment |  | 1,700 | 1,700 |  | 1,700 |  |  |  |
Other Assets and Deferred Charges [Member] | Alleghany and Bath County, Virginia |  |  |  |  |  |  |  |  |
Investments, Other Investments [Line Items] |  |  |  |  |  |  |  |  |
Carrying value of investment |  | 1,600 | 1,600 |  | 1,600 |  |  |  |
Alleghany and Bath County, Virginia |  |  |  |  |  |  |  |  |
Investments, Other Investments [Line Items] |  |  |  |  |  |  |  |  |
Gain (loss) on investment accounted for under the fair value method |  | (1,000) | 0 |  | 1,032 |  | 0 |  |
Unrealized Gain (Loss) on Investment Property |  |  | $ 0 |  | (1,032) |  | $ 0 |  |
Unrealized Gain Loss On Investment Property After Tax |  | $ (700) |  |  | $ 700 |  |  |  |
[1] | See Notes 1, 3, 4 and 17 for more information on losses associated with plant shutdowns, asset impairments and restructurings, unusual items, gains or losses from sale of assets, gains or losses on an investment accounted for under the fair value method and other items.

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