Number of shares that have been repurchased during the period and have not been retired and are not held in treasury. Some state laws may govern the circumstances under which an entity may acquire its own stock and prescribe the accounting treatment therefore. This element is used when state law does not recognize treasury stock.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
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Name:	us-gaap_StockRepurchasedDuringPeriodShares
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

Shareholders' Equity (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2021	Oct. 20, 2021	Jun. 30, 2021	Mar. 31, 2021
Equity, Class of Treasury Stock [Line Items]
Amount per quarter planned for stock repurchase	$ 10.0	$ 10.0		$ 10.0	$ 10.0
Share repurchased during period, shares	440,887	1,484,630
Average cost of repurchased stock (in dollars per share)	$ 22.68	$ 20.21
Stock Repurchase Program, Authorized Amount	$ 10.0	$ 10.0		$ 10.0	$ 10.0
Subsequent Event [Member]
Equity, Class of Treasury Stock [Line Items]
Amount per quarter planned for stock repurchase			$ 60.0
Stock Repurchase Program Authorized Increase Amount			15.0
Stock Repurchase Program, Authorized Amount			$ 60.0