Consolidated Statements Of Stockholders' Equity (Parenthetical) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Quarter 1 Dividend Payment [Member]
Regular dividends per share paid	$ 1.00	$ 1.00
Extra dividends per share paid	$ 5.00	$ 7.25
Quarter 4 Dividend Payment [Member]
Regular dividends per share paid	$ 1.00
Extra dividends per share paid	$ 5.50