Common Stock (Stock Repurchase Program) (Details) (USD $) In Thousands, except Share data, unless otherwise specified	159 Months Ended
	Mar. 31, 2012
Shares repurchased	25,406,184	[1]
Cost, including commission	$ 423,647	[1]
Total Remaining Shares Available For Repurchase at March 31, 2012	393,816

[1] Represents repurchased shares and cost since inception of the stock repurchase program in 1999.