Computation of Earnings Per Common Share - Narratives (Details) - $ / shares	Apr. 28, 2018	Sep. 15, 2015
Shares used in computing earnings per common share:
Weighted average stock price (usd per share)	$ 110.46
Convertible Note Hedge
Shares used in computing earnings per common share:
Debt instrument, convertible, conversion price (per share)	$ 96.89	$ 96.89
0.75% Convertible Senior Notes Due 2021
Shares used in computing earnings per common share:
Debt, interest rate (in percent)	0.75%
Debt instrument, convertible, conversion price (per share)		96.89
Class of warrant or right, exercise price of warrants or rights (per warrant)	$ 130.43	$ 130.43

Weighted Average Stock Price

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- Definition

Exercise price per share or per unit of warrants or rights outstanding.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(i)(4))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

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- Definition

The price per share of the conversion feature embedded in the debt instrument.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 5
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6928298&loc=SL6031898-161870

+ Details

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- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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- References

No definition available.

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- Details

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- Details

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