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Share-based compensation - Dividend equivalent rights - Summary of awards (Details) - $ / shares										9 Months Ended
	Mar. 04, 2021	Mar. 04, 2020	Nov. 04, 2019	Mar. 07, 2019	Apr. 04, 2018	Jan. 15, 2016	Mar. 06, 2015	Sep. 01, 2014	Mar. 12, 2014	Sep. 30, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Valuation Method	Black-Scholes	Black-Scholes		Black-Scholes	Black-Scholes	Monte Carlo	Monte Carlo	Monte Carlo	Monte Carlo
Dividend equivalent rights
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
SARs Awarded (in shares)			1,146,517							0
Service Period			2 years
Granted during the period, Weighted average fair value at grant date			$ 0.49							$ 0
Dividend Yield (as a percent)			2.93%
Risk-free rate of Return (as a percent)			2.06%
Expected Volatility (as a percent)			30.22%
Valuation Method			Monte Carlo

X

- Definition

Estimated period over which an employee is required to provide service in exchange for the equity-based payment award, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901

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- Definition

The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

+ References

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-Publisher FASB
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-Paragraph 2
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- Definition

The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

+ References

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-Publisher FASB
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- Definition

The estimated dividend rate (a percentage of the share price) to be paid (expected dividends) to holders of the underlying shares over the option's term.

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-Publisher FASB
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-SubTopic 10
-Section 50
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- Definition

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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Description of method used to estimate fair value of award under share-based payment arrangement.

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-Publisher FASB
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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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- Definition

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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No definition available.

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