Equity (Details) (USD $)	1 Months Ended	3 Months Ended		12 Months Ended
	Jan. 31, 2012	Mar. 31, 2012	Mar. 31, 2011	Dec. 31, 2011	Nov. 30, 2011	Mar. 28, 2011
Equity [Abstract]
Dividends per share						$ 13.60
Dividend payable		$ 417,606,000
Dividends payable date			Apr. 20, 2012
Voting common stock repurchased, authorized shares					800,000
Voting common stock repurchased, shares				136,494
Voting common stock repurchased				8,400,000
Treasury stock average price per share				$ 61.54
Portion of the stock repurchase settled	$ 500,000