Stock option activity (Details) - Stock Options $ / shares in Units, shares in Thousands, $ in Millions	12 Months Ended
Dec. 31, 2021 USD ($) $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding
Shares Outstanding at Beginning of Period	40
Shares Exercised	(40)
Shares Outstanding at End of Period	0
Weighted Average Exercise Price of Shares Outstanding at Beginning of Period \| $ / shares	$ 24.25
Weighted Average Exercise Price of Shares Exercised \| $ / shares	$ 24.25
Options Outstanding, Intrinsic Value \| $	$ 0.0

Amount by which the current fair value of the underlying stock exceeds the exercise price of options outstanding.

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- Definition

Number of options outstanding, including both vested and non-vested options.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

+ Details

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- Definition

Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

+ References

+ Details

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- Definition

Weighted average price at which option holders acquired shares when converting their stock options into shares.

+ References

No definition available.

+ Details

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- Definition

Number of share options (or share units) exercised during the current period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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