Per Share Data (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Per Share Data
Net Income attributable to Common Stockholders - Basic	$ 311,675	$ 254,921	$ 934,749	$ 1,115,776
Net Income attributable to Common Stockholders - Diluted	$ 311,675	$ 254,921	$ 934,749	$ 1,115,776
Weighted Average Shares Outstanding - Basic	310,332,777	304,107,489	310,194,789	301,029,029
Effect of stock options (in shares)		1,070	67	1,077
Weighted Average Shares Outstanding - Diluted	310,332,777	304,108,559	310,194,856	301,030,106