Acquisitions (Summary of Intangible Assets Acquired) (Details) - Hong Kong And Singapore Operations Of Royal Sun Alliance Insurance Plc $ in Millions	Apr. 02, 2015 USD ($)
Business Acquisition [Line Items]
Intangible assets acquired	$ 108.8
VOBA
Business Acquisition [Line Items]
Intangible assets acquired	28.9
Customer renewals
Business Acquisition [Line Items]
Intangible assets acquired	13.0
Distribution channels
Business Acquisition [Line Items]
Intangible assets acquired	66.9
SINGAPORE
Business Acquisition [Line Items]
Intangible assets acquired	74.1
SINGAPORE | VOBA
Business Acquisition [Line Items]
Intangible assets acquired	$ 17.8
Estimated useful life	2 years
SINGAPORE | Customer renewals
Business Acquisition [Line Items]
Intangible assets acquired	$ 8.6
Estimated useful life	4 years
SINGAPORE | Distribution channels
Business Acquisition [Line Items]
Intangible assets acquired	$ 47.7
Estimated useful life	18 years
HONG KONG
Business Acquisition [Line Items]
Intangible assets acquired	$ 34.7
HONG KONG | VOBA
Business Acquisition [Line Items]
Intangible assets acquired	$ 11.1
Estimated useful life	1 year 6 months
HONG KONG | Customer renewals
Business Acquisition [Line Items]
Intangible assets acquired	$ 4.4
Estimated useful life	5 years
HONG KONG | Distribution channels
Business Acquisition [Line Items]
Intangible assets acquired	$ 19.2
Estimated useful life	18 years