Consolidated Statements of Changes In Shareholders' Equity (Parenthetical) - $ / shares	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement of Stockholders' Equity [Abstract]
Cash dividends (in dollars per share)	$ 1.67	$ 1.60	$ 1.45
Class A Common Stock
Statement of Stockholders' Equity [Abstract]
Stock repurchases (shares)	813,090	998,910	382,000

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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Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration