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Share-Based Payments (Weighted-Average Fair Value of Options and Stock Per Share) (Details) - $ / shares | 12 Months Ended
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Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017
Restricted Stock Units (RSUs) [Member] |  |  |
Stock, weighted average grant date fair value | $ 63.60 | $ 55.96 | $ 42.66
Employee Stock Purchase Plan [Member] |  |  |
Options, weighted average grant date fair value | 4.32 | 2.67 | 2.73
Discount of grant date market value | 9.99 | 8.50 | 7.06
Total ESPP | 14.31 | 11.17 | 9.79
Agent Stock Purchase Plan [Member] |  |  |
Stock, weighted average grant date fair value | $ 7.00 | $ 5.99 | $ 5.04

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- Definition The weighted average fair value discount at grant date, for employee stock purchase plan shares issued during the period. + References No definition available. + Details
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- Definition The total weighted average fair value at grant date for employee stock purchase plan shares issued during the period. + References No definition available. + 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=116856206&loc=d3e5070-113901 + Details
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- Definition The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology. + 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)(1) -URI http://asc.fasb.org/extlink&oid=116856206&loc=d3e5070-113901 + Details
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