Consolidated Statements of Changes in Shareholders' Equity (Unaudited) (Parenthetical) - $ / shares	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Statement Of Stockholders Equity [Abstract]
Cash dividends declared per share	$ 0.28	$ 0.24	$ 0.80	$ 0.72
Issuance of treasury shares, shares			108