Consolidated Statements of Changes in Shareholders' Equity (Unaudited) (Parenthetical) - $ / shares	9 Months Ended
Sep. 30, 2018	Sep. 30, 2017
Consolidated Statements of Changes in Shareholders' Equity (Unaudited) [Abstract]
Cash dividend declared (in dollars per share)	$ 0.1994	$ 0.1969
Stock options exercised (in shares)	176,550	347,500
Purchase of treasury stock (in shares)	81,940	251,646
Sale of treasury stock (in shares)	202,009	231,571

Aggregate dividends declared during the period for each share of common stock outstanding.

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

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