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Incentive Plans (Narrative) (Details) |  | 1 Months Ended | 3 Months Ended |
--- | --- | --- | --- | ---
Aug. 30, 2013 USD ($) shares | Feb. 29, 2020 $ / shares peerCompanies | Mar. 31, 2021 USD ($) $ / shares | Mar. 31, 2020 USD ($) | Aug. 08, 2013 shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |
Share-based compensation | $ |  |  | $ 3,600,000 | $ 2,800,000 |
Performance Units |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |
Restricted stock units issued, weighted average grant date fair value (in dollars per share) |  |  | $ 145.91 |  |
2013 Long-Term Incentive Plan |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |
Number of shares authorized for incentive plan (no more than) (in shares) | shares | 5,500,000 |  |  |  |
Number of shares per employee (no more than) (in shares) | shares | 1,000,000 |  |  |  |
Award expiration period |  | 7 years |  |  |
2013 Long-Term Incentive Plan | Performance Units |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |
Maximum amount payable | $ | $ 5,000,000.0 |  |  |  |
2013 Long-Term Incentive Plan | Nonqualified Stock Options |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |
Shares granted, fair value (in dollars per share) |  | $ 32.00 |  |  |
2013 Long-Term Incentive Plan | Restricted Stock Units |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |
Award vesting period (in years) |  |  | 3 years |  |
2013 Long-Term Incentive Plan | Return on Average Capital Employed Performance Units |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |
Award vesting period (in years) |  | 3 years |  |  |
Restricted stock units issued, weighted average grant date fair value (in dollars per share) |  | $ 126.00 |  |  |
2013 Long-Term Incentive Plan | Total Shareholder Return Performance Units |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |
Award vesting period (in years) |  | 3 years |  |  |
Number of companies in total shareholder return peer comparison group | peerCompanies |  | 18 |  |  |
Restricted stock units issued, weighted average grant date fair value (in dollars per share) |  | $ 168.42 |  |  |
2013 Stock Plan For Non-Employee Directors |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |
Number of shares authorized for incentive plan (no more than) (in shares) | shares |  |  |  |  | 500,000
2013 Stock Plan For Non-Employee Directors | Restricted Stock Units |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |
Award vesting period (in years) |  |  | 3 years |  |
Restricted stock units issued, weighted average grant date fair value (in dollars per share) |  |  | $ 125.04 |  |

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- Definition Amount of expense for award under share-based payment arrangement. Excludes amount capitalized. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5047-113901 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SAB Topic 14.F) -URI http://asc.fasb.org/extlink&oid=115993241&loc=d3e301413-122809 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (h)(1)(i) -URI http://asc.fasb.org/extlink&oid=120381028&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://fasb.org/us-gaap/role/ref/legacyRef -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=120381028&loc=d3e5070-113901 + Details
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