Subsequent Event Subsequent Event (Details) (2012 Repurchase Program [Member], Common Stock [Member], Repurchase of Common Stock [Member], USD $) In Millions, unless otherwise specified	1 Months Ended
	May 31, 2011
2012 Repurchase Program [Member] | Common Stock [Member] | Repurchase of Common Stock [Member]
Subsequent Event [Line Items]
Stock Repurchase Program, Authorized Amount	$ 200.0