Debt (Senior Convertible Notes) (Narrative) (Details) (Convertible Debt [Member], Unsecured Debt [Member], USD $) In Millions, unless otherwise specified			3 Months Ended		0 Months Ended	3 Months Ended
	Mar. 31, 2014 2011 Convertible Notes [Member]	Dec. 31, 2013 2011 Convertible Notes [Member]	Mar. 31, 2014 2011 4.0% Notes [Member]	Mar. 31, 2014 2011 4.25% Notes [Member]	Mar. 31, 2014 Total Convertible Debt [Member] Plan [Member]	Mar. 31, 2014 Total Convertible Debt [Member] Plan [Member]
Debt Instrument [Line Items]
Unamortized debt discount and financing costs	$ 2.7	$ 4.0
Debt instrument, maturity date			Jun. 15, 2014	Dec. 15, 2014
Debt, intent to refinance, amount					$ 215.0
Debt, intent to refinance, description						The Company expects to refinance the $215.0 million principal amount of its senior convertible notes on a long-term basis either through its 2013 Credit Facility or through other sources of available funding and, therefore, has reflected the carrying amounts of these notes within long-term debt in the Company's condensed unaudited consolidated balance sheets.