Consolidated Statements of Stockholders' Equity (unaudited) (Parenthetical) - $ / shares	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Consolidated Statements of Stockholders' Equity (unaudited) [Abstract]
Cash dividends - per share (in dollars per share)	$ 0.69	$ 0.67
Purchase of treasury shares (in shares)		675,535
Net issuance of shares to employee benefit plans and other stock plans, including tax benefit (in shares)	271,148	389,058