Share-Based Compensation - Information pertaining to options oustanding - (Details) - $ / shares	3 Months Ended
Mar. 31, 2017	Mar. 31, 2016
Share-Based Compensation
Range of exercise prices, low end of range (in dollars per share)	$ 69.48	$ 61.42
Range of exercise prices, high end of range (in dollars per share)	$ 91.35	$ 69.48

The ceiling of a customized range of exercise prices for purposes of disclosing shares potentially issuable under outstanding stock option awards on all stock option plans and other required information pertaining to awards in the customized range.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (g)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

Name:	us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration