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Share-Based Compensation (Details) - USD ($) |  |  |  |  |  |  |  |  | 12 Months Ended
--- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Jan. 17, 2020 | Feb. 15, 2019 | Jan. 18, 2019 | Mar. 01, 2018 | Feb. 16, 2018 | Jan. 19, 2018 | Mar. 01, 2017 | Feb. 19, 2016 | Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |
Compensation expense |  |  |  |  |  |  |  |  | $ 3,000,000.0 | $ 1,100,000 | $ 1,000,000.0
Cash payments distributed related to awards previously granted and now payable |  |  |  |  |  |  |  |  | 1,500,000 |  |
Awards forfeited during period, value |  |  |  |  |  |  |  |  | $ 0 | $ 0 | $ 0
Awards forfeited during period, units |  |  |  |  |  |  |  |  | 0 | 0 | 0
Outstanding awards vested during period |  |  |  |  |  |  |  |  | $ 6,200,000 |  |
Performance Unit Plan [Member] | Performance Units [Member] |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |
Award vesting period |  |  |  |  |  |  |  |  | 5 years |  |
Awards granted (in units) |  | 17,022 |  |  | 17,830 |  | 14,704 | 19,055 |  |  |
Director Incentive Agreement [Member] | Performance Units [Member] |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |
Award vesting period |  |  |  |  |  |  |  |  | 3 years |  |
Awards granted (in units) |  |  | 5,175 | 1,106 |  | 4,704 |  |  |  |  |
Director Incentive Agreement [Member] | Performance Units [Member] | Subsequent Event [Member] |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |
Awards granted (in units) | 5,048 |  |  |  |  |  |  |  |  |  |

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- Definition The value of equity-based payment instruments, excluding stock (or unit) options, that were forfeited during the reporting period. + References No definition available. + Details
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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=116856206&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=116856206&loc=d3e5070-113901 + Details
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- Definition Period over which grantee's right to exercise award under share-based payment arrangement is no longer contingent on satisfaction of service or performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, combination of market, performance or service condition. + 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)(1) -URI http://asc.fasb.org/extlink&oid=116856206&loc=d3e5070-113901 + 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://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=116856206&loc=d3e5070-113901 + Details
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- Definition Amount of cash paid to settle liability for award under share-based payment arrangement. + 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 (d)(2) -URI http://asc.fasb.org/extlink&oid=116856206&loc=d3e5070-113901 + Details
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- Definition Fair value of share-based awards for which the grantee gained the right by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash. + 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 (d)(2) -URI http://asc.fasb.org/extlink&oid=116856206&loc=d3e5070-113901 + Details
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