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Stock-Based Compensation (Stock Appreciation Rights Award Activity) (Details) - $ / shares | 12 Months Ended
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Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016
SARs, Weighted Average Exercise Price [Roll Forward] |  |  |
Stock-Settled SARs, Outstanding | 14,160 |  |
Cash-Settled SARs, Outstanding | 25,659 |  |
Stock Appreciation Rights (SARs) [Member] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Awards, expiration period | 10 years |  |
SARs Activity [Roll Forward] |  |  |
Outstanding, Beginning | 51,368 | 116,087 | 232,930
Granted | 3,480 | 2,792 | 3,368
Exercised | (14,629) | (67,511) | (114,976)
Forfeited | (400) | 0 | (5,235)
Outstanding, Ending | 39,819 | 51,368 | 116,087
Exercisable | 30,285 | 39,769 | 71,701
SARs, Weighted Average Exercise Price [Roll Forward] |  |  |
Oustanding, Beginning (in usd per share) | $ 38.55 | $ 31.13 | $ 27.79
Granted (in usd per share) | 89.64 | 83.47 | 68.40
Exercised (in usd per share) | 28.45 | 27.65 | 24.95
Forfeited (in usd per share) | 63.43 | 0.00 | 42.28
Oustanding, Ending (in usd per share) | 46.48 | 38.55 | 31.13
Exercisable (in usd per share) | $ 36.91 | $ 30.77 | $ 26.65

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- Definition Period from grant date that an equity-based award expires, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a)(2) -URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901 + Details
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