Discontinued Operations - Disposal Group Income Statement (Details) - USD ($) $ in Millions	1 Months Ended		3 Months Ended		6 Months Ended
	Apr. 30, 2016	Apr. 29, 2016	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Income from discontinued operations, net of tax			$ 1.9	$ 18.7	$ 4.8	$ 37.2
Discontinued Operations, Held-for-sale | Customer Communications
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Operating revenues			14.0	151.7	53.4	311.5
Out-of-pocket reimbursements			3.5	184.1	12.8	389.4
Total revenues			17.5	335.8	66.2	700.9
Costs and expenses			19.0	314.7	63.8	649.8
Depreciation and amortization			0.0	5.7	0.0	11.9
Operating income (loss)			(1.5)	15.4	2.4	39.2
Equity in earnings of unconsolidated affiliates			0.1	0.3	0.2	0.2
Net gain on business disposition			2.9	0.0	2.9	0.0
Income before income taxes			1.5	15.7	5.5	39.4
Income taxes			(0.4)	(3.0)	0.7	2.2
Income from discontinued operations, net of tax			1.9	$ 18.7	$ 4.8	$ 37.2
United Kingdom | Customer Communications
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net gain on business disposition			$ 2.9
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