Consolidated Statements of Changes in Shareholders' Equity (Unaudited) (Parenthetical) - $ / shares	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Consolidated Statements of Changes in Shareholders' Equity (Unaudited) [Abstract]
Cash dividend declared (in dollars per share)	$ 0.1312	$ 0.1312
Stock options exercised (in shares)	95,200	296,300
Purchase of treasury stock (in shares)	45,509	213,356
Sale of treasury stock (in shares)	136,081	151,762