CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY (Parenthetical) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Common stock issued for stock grants- Gross (in shares)	5,334	6,170	7,475
Common stocks issued for employee gifts (in shares)			74
Common stock, forfeited (in shares)	1,241
Dividends per share (in dollars per share)	$ 1.16	$ 1.08	$ 1.00
Director
Common stock issued for stock grants- Gross (in shares)	1,386	1,352
Common stock, forfeited (in shares)		1,181
Common stock issued - Stock options exercised (in shares)	$ 600