Consolidated Statements of Changes In Shareholders' Equity (Parenthetical) - $ / shares	3 Months Ended	9 Months Ended
Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Stock repurchased during period (in shares)	117,700	295,900	813,090	744,400
Statement of Stockholders' Equity [Abstract]
Cash dividends (in dollars per share)	$ 0.40	$ 0.40	$ 1.20	$ 1.20
Common Stock \| Class A Common Stock
Stock repurchased during period (in shares)	117,700	295,900	813,090	744,400

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.

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Balance Type:	na
Period Type:	duration