Consolidated Statements of Equity (Parenthetical) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Number of shares of common stock issued under stock option plan	582,730	268,978	374,508
Number of common stock shares purchased	251,312	115,460	250,070
Preferred stock	$ 1.375	$ 1.375	$ 1.375
Common stock	$ 0.58	$ 0.53	$ 0.49
Common Stock Split Ratio Declared	2
Common Stock
Number of shares of common stock issued under stock option plan	582,730	268,978	374,508
Additional Paid-in Capital
Number of shares of common stock issued under stock option plan	582,730	268,978	374,508
Treasury Stock
Number of common stock shares purchased	251,312	115,460	250,070
Retained Earnings
Preferred stock	$ 1.375	$ 1.375	$ 1.375
Common stock	$ 0.58	$ 0.53	$ 0.49