Consolidated Statements of Stockholders' Equity (Parenthetical) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Stockholders dividends per share	$ 3.50	$ 5.25	$ 8.00
Adjustment paid to stock plan participants per share	$ 3.00	$ 4.75	$ 7.50
Retained Earnings
Stockholders dividends per share	$ 3.50	$ 5.25	$ 8.00
Adjustment paid to stock plan participants per share	$ 3.00	$ 4.75	$ 7.50