Savings Plans, Pension Plans and Other Postretirement Employee Benefits (Fair Value Measurements) (Details) - Pension Plans [Member] - USD ($) $ in Thousands |
Dec. 31, 2018 |
Dec. 31, 2017 |
Dec. 31, 2016 |
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Fair Value of Plan Assets | $ 351,285 | $ 313,862 | $ 289,675 | |||||||||||
Cash and Cash Equivalents [Member] | ||||||||||||||
Fair Value of Plan Assets | 4,120 | 3,004 | ||||||||||||
Domestic Equity Securities [Member] | ||||||||||||||
Fair Value of Plan Assets | [1] | 54,699 | 57,560 | |||||||||||
International Equity Securities [Member] | ||||||||||||||
Fair Value of Plan Assets | [2] | 21,848 | 28,413 | |||||||||||
Emerging Markets [Member] | ||||||||||||||
Fair Value of Plan Assets | [3] | 28,134 | 29,257 | |||||||||||
Fixed Income Securities [Member] | ||||||||||||||
Fair Value of Plan Assets | [4] | 204,072 | 148,833 | |||||||||||
Alternative Securities [Member] | ||||||||||||||
Fair Value of Plan Assets | [5] | 38,412 | 46,795 | |||||||||||
Level 1 [Member] | ||||||||||||||
Fair Value of Plan Assets | 246,416 | 181,027 | ||||||||||||
Level 1 [Member] | Cash and Cash Equivalents [Member] | ||||||||||||||
Fair Value of Plan Assets | 4,120 | 3,004 | ||||||||||||
Level 1 [Member] | Domestic Equity Securities [Member] | ||||||||||||||
Fair Value of Plan Assets | [1] | 31,315 | 29,178 | |||||||||||
Level 1 [Member] | Emerging Markets [Member] | ||||||||||||||
Fair Value of Plan Assets | [3] | 6,909 | 12 | |||||||||||
Level 1 [Member] | Fixed Income Securities [Member] | ||||||||||||||
Fair Value of Plan Assets | [4] | 204,072 | 148,833 | |||||||||||
Level 2 [Member] | ||||||||||||||
Fair Value of Plan Assets | 104,869 | 132,835 | ||||||||||||
Level 2 [Member] | Domestic Equity Securities [Member] | ||||||||||||||
Fair Value of Plan Assets | [1] | 23,384 | 28,382 | |||||||||||
Level 2 [Member] | International Equity Securities [Member] | ||||||||||||||
Fair Value of Plan Assets | [2] | 21,848 | 28,413 | |||||||||||
Level 2 [Member] | Emerging Markets [Member] | ||||||||||||||
Fair Value of Plan Assets | [3] | 21,225 | 29,245 | |||||||||||
Level 2 [Member] | Alternative Securities [Member] | ||||||||||||||
Fair Value of Plan Assets | [5] | $ 38,412 | $ 46,795 | |||||||||||
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