Stock Transactions Stock Transactions (Narrative) (Details) (USD $)	9 Months Ended	1 Months Ended			9 Months Ended	0 Months Ended
	Sep. 30, 2013	Jan. 24, 2013 January 2013 Share Repurchase Authorization [Member]	Apr. 18, 2013 April 2013 Share Repurchase Authorization [Member]	Apr. 30, 2013 April 2013 Share Repurchase Authorization [Member]	Sep. 30, 2013 July 2013 Share Repurchase Authorization	Jul. 18, 2013 Subsequent Event	Jul. 18, 2013 Subsequent Event July 2013 Share Repurchase Authorization
Equity, Class of Treasury Stock [Line Items]
Treasury Stock, Shares, Acquired		815,011		2,865,132	471,169
Treasury Stock, Value, Acquired, Cost Method		$ 47,600,000		$ 182,900,000	$ 30,800,000
Stock Repurchase Program, Authorized Amount		200,000,000.0	100,000,000			400,000,000	100,000,000
Stock Repurchase Program, Remaining Authorized Repurchase Amount	$ 138,700,000