Consolidated Statements of Changes in Shareholders' Equity (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement Consolidated Statements Of Changes In Shareholders Equity Parenthetical Unaudited [Abstract]
Cash dividend declared per share	$ 0.39	$ 0.28	$ 0.24
Treasury shares reissued shares			1
Treasury shares purchased shares, net of reissued			123,065
Treasury shares purchased shares	12,863