Convertible Perpetual Preferred Stock - Table 2 (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Temporary Equity [Abstract]
Excess exchanged in transaction	$ 71.6	$ 0.8	$ 0
Convertible Preferred Stock [Member]
Temporary Equity [Abstract]
Carrying value of shares repurchased	249.0	45.2
Cumulative dividends included as part of purchase price	2.2	0.5
Excess exchanged in transaction	71.6	0.8
Temporary Equity, Consideration Exchanged for Repurchase	$ 322.8	$ 46.5