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Benefit Plans (Summary Of Performance Shares and Performance Units Vested Awards) (Details) - USD ($) $ in Millions | 12 Months Ended
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Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
Performance Shares [Member] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Vested (in shares/awards) | 99,438 | 98,186 | 91,224
Performance Units [Member] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Vested (in shares/awards) | 37,395 | 42,760 | 45,690
2014 Grant [Member] | Performance Shares [Member] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Vested (in shares/awards) | 99,438 |  |
Vested percentage of the target | 147.50% |  |
Cash and stock payout value | $ 5.6 |  |
Cash payout value | $ 5.1 |  |
Common stock shares from vested performance shares (in shares) | 5,185 |  |
2014 Grant [Member] | Performance Units [Member] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Vested (in shares/awards) | 37,395 |  |
Vested percentage of the target | 147.50% |  |
Cash and stock payout value | $ 1.5 |  |
Cash payout value | $ 1.5 |  |
2013 Grant [Member] | Performance Shares [Member] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Vested (in shares/awards) |  | 98,186 |
Vested percentage of the target |  | 165.00% |
Cash and stock payout value |  | $ 5.1 |
Cash payout value |  | $ 2.9 |
Common stock shares from vested performance shares (in shares) |  | 22,408 |
2013 Grant [Member] | Performance Units [Member] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Vested (in shares/awards) |  | 42,760 |
Vested percentage of the target |  | 165.00% |
Cash and stock payout value |  | $ 1.7 |
Cash payout value |  | $ 1.7 |
2012 Grant [Member] | Performance Shares [Member] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Vested (in shares/awards) |  |  | 91,224
Vested percentage of the target |  |  | 167.50%
Cash and stock payout value |  |  | $ 5.1
Cash payout value |  |  | $ 3.2
Common stock shares from vested performance shares (in shares) |  |  | 21,950
2012 Grant [Member] | Performance Units [Member] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Vested (in shares/awards) |  |  | 45,690
Vested percentage of the target |  |  | 167.50%
Cash and stock payout value |  |  | $ 1.6
Cash payout value |  |  | $ 1.6

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- Definition Costs and payments related to employee benefits and equity-based compensation, such as pension expense and contributions, other postretirement benefits expense and payments, stock or unit options expense, and amortization of restricted stock or unit. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3602-108585 + Details
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- Definition Aggregate cash paid by the entity during the period to settle equity instruments granted under equity-based payment arrangements. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (k) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The number of equity-based payment instruments, excluding stock (or unit) options, that vested during the reporting period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2)(iii)(2) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition Number of share instruments newly issued under a share-based compensation plan. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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