Consolidated Statements of Changes in Stockholders' Equity (Parenthetical) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Consolidated Statements of Changes in Stockholders' Equity [Abstract]
Cash dividends - per share (in dollars per share)	$ 0.80	$ 0.80	$ 0.80
Net issuance of common shares (in shares)			23,810
Purchase of treasury shares (in shares)	769,568	1,458,609
Net issuance of shares for acquisition (in shares)	1,269,592
Net issuance of shares to employee stock plans, including tax benefit (in shares)	118,616	112,512	141,146