Other Employee Benefit Plans - Shares purchased (Details) - ESPP - $ / shares	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares purchased	4,918	4,647	4,718
Average price per share	$ 126.83	$ 100.34	$ 77.05

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

+ Details

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- Definition

The weighted average of per share prices paid for shares purchased on the open market for issuance to employees under the 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
-URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5047-113901

+ Details

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- Definition

The number of shares purchased on the open market during the period for issuance to employees under the plan.

+ References

+ Details

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