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Stock-Based Compensation (Textuals) (Details) | 12 Months Ended
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Dec. 31, 2017 USD ($) plan $ / shares shares | Dec. 31, 2016 USD ($) $ / shares shares | Dec. 31, 2015 USD ($) $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Other charges | $ | $ 0 | $ 200,000 | $ 0
Share-based Compensation, Executive Retirements | $ |  |  | $ 10,400,000
Shares available for grant/issuance | 4,597,102 |  |
Unrecognized compensation expense for all nonvested awards | $ | $ 17,200,000 |  |
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition | 1 year 7 months |  |
Employee Stock Option [Member] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Awards, expiration period | 10 years |  |
Number of shares reduced for each award granted | 1 |  |
Stock Appreciation Rights (SARs) [Member] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Vesting period | 4 years |  |
Awards, expiration period | 10 years |  |
Award Types Other than Stock Options and Stock Appreciation Rights [Member] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Number of shares reduced for each award granted | 2.5 |  |
Performance-Vesting Shares [Member] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period | 92,045 | 115,035 | 147,908
Granted at target level | $ / shares | $ 84.01 | $ 60.47 | $ 55.49
Employee Stock Purchase Plan (ESPP) [Member] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Shares available for grant/issuance | 4,000,000 |  |
Percentage of current market price for sales to eligible employees | 85.00% |  |
Limitation on payroll deductions of employee's base salary, percent | 25.00% |  |
Limitation on payroll deductions of employee's base salary, amount | $ | $ 25,000 |  |
Maximum number of shares per employee | 2,000 |  |
Maximum number of shares per employee, per year | 8,000 |  |
Purchases of shares | 56,218 | 60,839 | 61,757
Annual Incentive Plan [Member] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period | 1,800 | 2,400 | 1,500
Vesting period | 4 years |  |
Granted at target level | $ / shares | $ 86.93 | $ 59.64 | $ 51.53
Performance-Vesting Units [Member] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period | 598 | 419 | 1,386
Granted at target level | $ / shares | $ 83.47 | $ 59.64 | $ 54.14
Minimum [Member] | Performance-Vesting Shares [Member] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Actual payout range | 0.00% |  |
Minimum [Member] | Performance-Vesting Units [Member] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Actual payout range | 0.00% |  |
Maximum [Member] | Performance-Vesting Shares [Member] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Actual payout range | 200.00% |  |
Maximum [Member] | Performance-Vesting Units [Member] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Actual payout range | 200.00% |  |
Deferred Compensation Plans [Member] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Deferred Compensation Arrangement with Individual, Conversion Unit | 1 |  |
Number of deferred compensation plans | plan | 2 |  |
Number of deferred stock units | 402,155 |  |
Number of deferred stock units payable in cash | 24,296 |  |
Deferred Compensation Plans [Member] | Non-Employee Directors [Member] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period | 17,284 |  |
Granted at target level | $ / shares | $ 94.68 |  |

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- Definition Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + 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 (i) -URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901 + Details
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- Definition Amount of other expenses associated with exit or disposal activities pursuant to an authorized plan. Excludes expenses associated with a discontinued operation or an asset retirement obligation. + 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 (b) -URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3602-108585 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 420 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SAB Topic 5.P.4(b)) -URI http://asc.fasb.org/extlink&oid=27011515&loc=d3e140904-122747 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 420 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SAB Topic 5.P.3) -URI http://asc.fasb.org/extlink&oid=27011515&loc=d3e140864-122747 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 420 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6394359&loc=d3e17939-110869 + Details
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- Definition The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target 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 -Subparagraph (c)(2)(iii)(1) -URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901 + Details
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- Definition The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target 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 -Subparagraph (c)(2)(iii)(1) -URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901 + Details
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- Definition The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable. + 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=96867065&loc=d3e5070-113901 + Details
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