Investments Mortgages by Year of Origination (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013		Dec. 31, 2012
Investment [Line Items]
Total Commercial mortgage loans	$ 3,397.3	[1]	$ 2,874.0	[1]
Year of Origination 2013
Investment [Line Items]
Total Commercial mortgage loans	785.2	[1]	0	[1]
Year of Origination 2012
Investment [Line Items]
Total Commercial mortgage loans	908.1	[1]	939.0	[1]
Year of Origination 2011
Investment [Line Items]
Total Commercial mortgage loans	792.8	[1]	836.9	[1]
Year of Origination 2010
Investment [Line Items]
Total Commercial mortgage loans	121.1	[1]	124.0	[1]
Year of Origination 2009
Investment [Line Items]
Total Commercial mortgage loans	68.4	[1]	73.0	[1]
Year of Origination 2008
Investment [Line Items]
Total Commercial mortgage loans	89.0	[1]	119.0	[1]
Year of Origination 2007 and Prior
Investment [Line Items]
Total Commercial mortgage loans	$ 632.7	[1]	$ 782.1	[1]

[1] Balances do not include allowance for mortgage loan credit losses.