Capital Stock (Details) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2008
Capital Stock
Common stock authorized (in shares)	150,000,000
Preferred stock authorized (in shares)	4,000,000
Common stock authorized, par value (in dollars per share)	$ 1.25	$ 1.25
Preferred stock authorized, par value (in dollars per share)	$ 1.25
Repurchase of shares of common stock
Number of Shares authorized to be Purchased		2,000,000	2,000,000	1,536,647
Additional Shares Authorized for Purchase			463,353
Shares Purchased	286,577
Remaining Shares Authorized for Purchase	1,713,423	2,000,000	2,000,000
Preferred Stock Purchase Rights Agreement
Preferred stock purchase rights
Number of rights distributed for each share of common stock outstanding	1
Minimum percentage of common stock to be acquired to trigger exercise of rights	15.00%
Number of securities called by rights (in shares)	0.01
Exercise price of rights (in dollars per share)	$ 230
Multiplier of exercise price of right to determine common share purchase rights	2
Redemption price per right (in dollars per share)	$ 0.001
Number of business days following the acquisition of stock after which rights become exercisable	10
Preferred stock reserved for issuance upon exercise of rights (in shares)	804,772	805,141