Discontinued Operations - Disposal Group Income Statement (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended		9 Months Ended
	Apr. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Income (loss) from discontinued operations, net of tax		$ (0.3)	$ 222.8	$ 4.5	$ 260.0
Discontinued Operations, Held-for-sale | Customer Communications
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Operating revenues		0.0	38.2	53.4	349.7
Out-of-pocket reimbursements		0.0	9.9	12.8	399.3
Total revenues		0.0	48.1	66.2	749.0
Costs and expenses		0.0	53.7	63.8	703.5
Depreciation and amortization		0.0	0.0	0.0	11.9
Operating income (loss)		0.0	(5.6)	2.4	33.6
Equity in earnings of unconsolidated affiliates		0.0	0.1	0.2	0.3
Net gain (loss) on business disposition		(0.3)	340.1	2.6	340.1
Income (loss) before income taxes		(0.3)	334.6	5.2	374.0
Income taxes		0.0	111.8	0.7	114.0
Income (loss) from discontinued operations, net of tax		$ (0.3)	$ 222.8	4.5	$ 260.0
United Kingdom | Customer Communications
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net gain (loss) on business disposition				$ 2.6
Customer Communications | United Kingdom
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sale Leaseback Transaction, Net Proceeds, Investing Activities	$ 16.0
Sale Leaseback Transaction, Operating Lease Term	12 years
Sale Leaseback Transaction, Portion of Building Leased, Percent	66.67%
Sale Leaseback Transaction, Annual Rental Payments	$ 0.7