Acquisition of Business Intangible Assets Acquired (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Apr. 30, 2015
Broker Relationships [Member]
Schedule of Intangible Assets Acquired by Class [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets	$ 16.8	$ 18.1	$ 18.9
Useful life of intangibles acquired (in years)	15 years
Intangible Assets Arising from Insurance Contracts Acquired in Business Combination [Member]
Schedule of Intangible Assets Acquired by Class [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets	$ 0.0	0.2	9.2
Other Intangible Assets [Member]
Schedule of Intangible Assets Acquired by Class [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets	2.5	3.7	4.5
Finite-Lived Intangible Assets [Member]
Schedule of Intangible Assets Acquired by Class [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets	$ 19.3	$ 22.0	$ 32.6
Minimum [Member]
Schedule of Intangible Assets Acquired by Class [Line Items]
Useful life of intangibles acquired (in years)	2 years
Maximum [Member]
Schedule of Intangible Assets Acquired by Class [Line Items]
Useful life of intangibles acquired (in years)	5 years