Consolidated Statements of Changes in Shareholders' Equity (Parenthetical)	12 Months Ended
	Dec. 31, 2017 $ / shares	Dec. 31, 2016 $ / shares	Dec. 31, 2015 $ / shares
Statement of Stockholders' Equity [Abstract]
Cash dividends, (in dollars per share)	$ 0.52	$ 0.48	$ 0.45