Long-term Debt Senior Notes (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended			0 Months Ended				3 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Oct. 02, 2012 Series B senior notes [Member]	Jul. 27, 2005 Series B senior notes [Member]	Jul. 27, 2012 Series C senior notes [Member]	Jul. 27, 2005 Series C senior notes [Member]	Dec. 31, 2012 Senior Notes [Member]
Debt Instrument [Line Items]
Debt instrument, face amount					$ 100.0		$ 25.0
Debt instrument, interest rate, stated percentage					5.36%
Debt instrument, maturity date					Jul. 26, 2015	Jul. 26, 2012
Repayments of notes payable				100.0
Prepayment Penalty On Debt				12.6
Debt Instrument, Description of Variable Rate Basis							three-month LIBOR plus 0.70%
Write off of Deferred Debt Issuance Cost	$ 0.5	$ 3.2	$ 0.5					$ 0.3