Derivatives Forward Contracts (Details) - Forward Contracts SEK in Millions, $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2015 USD ($)	Jun. 30, 2015 USD ($)	Jun. 30, 2014 USD ($)	Jun. 30, 2015 SEK	Dec. 31, 2014 USD ($)
Derivative Instruments, Gain (Loss) [Line Items]
Realized and unrealized gains (losses)	$ 0.4
Sirius Group
Derivative Instruments, Gain (Loss) [Line Items]
Notional amount	31.9	$ 31.9		SEK 262.7	$ 33.1
Realized and unrealized gains (losses)		0.0	$ (0.1)
Carrying Value	$ (0.2)	$ (0.2)			$ 0.0