Fair Value (Fair Value And Carrying Value Of Senior Notes) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Debt Instrument [Line Items]
Fair value	$ 745.1	$ 684.8
Carrying value	699.6	649.6
Unamortized discount	0.4	0.4
2013 Senior Notes [Member]
Debt Instrument [Line Items]
Fair value	0	356.7
Carrying value	0	350.0
Unamortized discount	0	0
2018 Senior Notes [Member]
Debt Instrument [Line Items]
Fair value	335.8	328.1
Carrying value	299.6	299.6
Unamortized discount	0.4	0.4
2020 Senior Notes [Member]
Debt Instrument [Line Items]
Fair value	409.3	0
Carrying value	400.0	0
Unamortized discount	$ 0	$ 0