Investments - Schedule of Summarized Financial Information for Ceridian (Details) - Ceridian - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Condensed Combined Balance Sheets
Total current assets before customer funds	$ 308.9		$ 308.9		$ 342.7
Customer funds	3,480.8		3,480.8		3,702.8
Goodwill and other intangible assets, net	2,308.9		2,308.9		2,290.9
Other assets	97.1		97.1		90.1
Total assets	6,195.7		6,195.7		6,426.5
Current liabilities before customer obligations	144.8		144.8		200.8
Customer obligations	3,480.3		3,480.3		3,692.3
Long-term obligations, less current portion	1,118.9		1,118.9		1,139.8
Other long-term liabilities	264.4		264.4		300.5
Total liabilities	5,008.4		5,008.4		5,333.4
Equity	1,187.3		1,187.3		1,093.1
Total liabilities and equity	6,195.7		6,195.7		$ 6,426.5
Condensed Combined Statements of Earnings
Total revenues	184.5	$ 169.9	548.3	$ 514.9
Loss before income taxes	(16.3)	(36.9)	(46.3)	(76.6)
Net loss	$ (20.0)	$ (40.2)	$ (54.0)	$ (63.7)