The estimated measure of the percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period.

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-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
-Section 50
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The risk-free interest rate assumption that is used in valuing an option on its own shares.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
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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.

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Share and Unit-based Plans - Schedule LTIP Units Valuation Assumptions (Details) - LTIP units	Jan. 29, 2018	Jan. 01, 2018	Jun. 01, 2017	Jan. 01, 2017	Jan. 01, 2016
January 1, 2016
Share and unit-based plans
Risk Free Interest Rate					1.32%
Expected Volatility					20.31%
January 1, 2017
Share and unit-based plans
Risk Free Interest Rate				1.49%
Expected Volatility				20.75%
June 1, 2017
Share and unit-based plans
Risk Free Interest Rate			1.45%
Expected Volatility			21.40%
January 1, 2018
Share and unit-based plans
Risk Free Interest Rate		1.98%
Expected Volatility		23.38%
January 29, 2018
Share and unit-based plans
Risk Free Interest Rate	2.25%
Expected Volatility	23.86%