Property and Equipment (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Properties [Line items]
Cost	$ 1,132.5	$ 1,131.1
Less accumulated depreciation and amortization	896.8	874.4
Properties, net	235.7	256.7
Aggregate Principle of IRB	87.6	73.2
Assets under capital lease, net	2.5	11.8
Assets under capital lease, accumulated depreciation	2.2	10.7
Depreciation
Depreciation expense	78.2	77.6	$ 80.7
Land
Properties [Line items]
Cost	34.2	35.9
Buildings
Properties [Line items]
Cost	160.3	181.5
Technology equipment
Properties [Line items]
Cost	213.0	200.5
Software
Properties [Line items]
Cost	508.2	489.4
Software | Business combinations
Properties [Line items]
Cost	57.7
Properties, net	14.5	14.5
Furniture, fixtures and other equipment
Properties [Line items]
Cost	122.1	138.0
Leasehold improvements
Properties [Line items]
Cost	76.4	72.2
Construction-in-progress
Properties [Line items]
Cost	18.3	13.6
Capitalized software development costs
Software development and maintenance costs
Capitalized software development costs	21.5	23.3	28.8
Amortization of capitalized software development costs	$ 22.9	$ 25.5	$ 25.3