Schedule I (Parent Co Statement of Comprehensive Income) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Net income (loss)	$ 394.0	$ 271.2	$ 218.0
Other comprehensive income (loss)	34.0	1.6	(66.3)
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	428.0	272.8	132.1
Parent
Net income (loss)	394.0	271.2	198.4
Other comprehensive income (loss)	34.0	1.6	(66.3)
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	$ 428.0	$ 272.8	$ 132.1