Other Benefit Plans (Schedule of Employees Eligible to Participate in Employee Stock Purchase Plan) (Details) - $ / shares	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plans And Other Postretirement Benefit Plans Disclosures [Abstract]
ESPP shares purchased	8,005	5,151	4,132
Average purchase price per share	$ 19.324	$ 26.015	$ 28.716

Number of shares issued during the period as a result of an employee stock purchase plan.

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