Share-Based Compensation Plans - Weighted Average Exercise Price, ESPP (Details) - Employee Stock Purchase Plan - $ / shares shares in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted and exercised (in shares)	199	160	192,000
Weighted average exercise plan (in usd per share)	$ 54.89	$ 66.72	$ 56.17

The weighted average of per share prices paid for shares purchased on the open market for issuance to employees under the plan.

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

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Balance Type:	na
Period Type:	instant