Segment and Geographic Information (Details) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2016 USD ($)	Sep. 30, 2016 USD ($)	Jun. 30, 2016 USD ($)	Mar. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Sep. 30, 2015 USD ($)	Jun. 30, 2015 USD ($)	Mar. 31, 2015 USD ($)	Dec. 31, 2016 USD ($) segment	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Summary of financial information of segments
Number of operating segments | segment									2
Revenues	$ 373.7	$ 365.5	$ 373.9	$ 361.3	$ 362.3	$ 353.4	$ 349.3	$ 340.0	$ 1,474.4	$ 1,405.0	$ 1,445.5
Out-of-pocket reimbursements	25.1	21.2	16.6	19.4	20.9	18.2	14.2	15.7	82.3	69.0	59.3
Total revenues	398.8	386.7	390.5	380.7	383.2	371.6	363.5	355.7	1,556.7	1,474.0	1,504.8
Costs and expenses	296.5	289.6	320.4	306.9	295.9	287.1	289.7	277.5	1,213.4	1,150.2	1,149.1
Depreciation and amortization	26.9	22.8	24.2	22.1	25.1	22.9	21.7	21.4	96.0	91.1	93.0
Operating income (loss)	75.4	74.3	45.9	51.7	62.2	61.6	52.1	56.8	247.3	232.7	262.7
Other income (loss), net	2.7	6.7	7.0	6.3	14.6	14.4	92.2	83.3	22.7	204.5	373.1
Gain on sale of business	5.5	0.0	0.0	0.0					5.5	0.0	100.5
Equity in earnings of unconsolidated affiliates	3.3	7.0	10.2	6.7	6.2	11.8	12.7	14.7	27.2	45.4	34.7
Earnings from continuing operations before interest, income taxes and non-controlling interest									302.7	482.6	771.0
Interest expenses	5.5	$ 5.4	$ 6.5	$ 6.1	6.1	$ 5.8	$ 5.8	$ 6.1	23.5	23.8	26.3
Assets	2,771.8				2,813.2				2,771.8	2,813.2
Operating
Summary of financial information of segments
Revenues									1,474.4	1,405.0	1,445.5
Operating | Financial Services
Summary of financial information of segments
Revenues									1,047.3	1,025.5	1,056.3
Out-of-pocket reimbursements									73.9	61.7	52.6
Total revenues									1,164.1	1,125.5	1,141.4
Costs and expenses									908.3	869.8	867.9
Depreciation and amortization									79.7	71.6	72.2
Operating income (loss)									176.1	184.1	201.3
Other income (loss), net									(2.2)	(2.1)	19.5
Gain on sale of business									5.5		100.5
Equity in earnings of unconsolidated affiliates									21.2	35.3	29.8
Earnings from continuing operations before interest, income taxes and non-controlling interest									200.6	217.3	351.1
Assets	1,717.1				1,611.2				1,717.1	1,611.2
Operating | Healthcare Services
Summary of financial information of segments
Revenues									426.2	376.4	382.1
Out-of-pocket reimbursements									8.5	8.2	6.9
Total revenues									434.7	384.6	389.0
Costs and expenses									345.1	321.3	308.5
Depreciation and amortization									15.6	18.6	19.5
Operating income (loss)									74.0	44.7	61.0
Other income (loss), net									0.1	(0.1)	0.1
Gain on sale of business									0.0		0.0
Equity in earnings of unconsolidated affiliates									0.5	0.3	0.5
Earnings from continuing operations before interest, income taxes and non-controlling interest									74.6	44.9	61.6
Assets	552.2				405.3				552.2	405.3
Operating | Investments/Other
Summary of financial information of segments
Revenues									0.9	3.1	7.1
Out-of-pocket reimbursements									0.0	0.0	0.0
Total revenues									0.9	3.1	7.1
Costs and expenses									3.0	(1.7)	5.4
Depreciation and amortization									0.7	0.9	1.3
Operating income (loss)									(2.8)	3.9	0.4
Other income (loss), net									24.8	206.7	353.5
Gain on sale of business									0.0		0.0
Equity in earnings of unconsolidated affiliates									5.5	9.8	4.4
Earnings from continuing operations before interest, income taxes and non-controlling interest									27.5	220.4	358.3
Assets	431.4				502.7				431.4	502.7
Intersegment Operating/Elimination/Adjustments
Summary of financial information of segments
Revenues									(42.9)	(38.3)	(32.5)
Out-of-pocket reimbursements									(0.1)	(0.9)	(0.2)
Total revenues									(43.0)	(39.2)	(32.7)
Costs and expenses									(43.0)	(39.2)	(32.7)
Depreciation and amortization									0.0	0.0	0.0
Operating income (loss)									0.0	0.0	0.0
Other income (loss), net									0.0	0.0	0.0
Gain on sale of business									0.0		0.0
Equity in earnings of unconsolidated affiliates									0.0	0.0	0.0
Earnings from continuing operations before interest, income taxes and non-controlling interest									0.0	0.0	0.0
Assets	(1.5)				(3.5)				(1.5)	(3.5)
Intersegment Operating/Elimination/Adjustments | Financial Services
Summary of financial information of segments
Revenues									42.9	38.3	32.5
Intersegment Operating/Elimination/Adjustments | Healthcare Services
Summary of financial information of segments
Revenues									0.0	0.0	0.0
Intersegment Operating/Elimination/Adjustments | Investments/Other
Summary of financial information of segments
Revenues									0.0	0.0	$ 0.0
Discontinued Operations, Held-for-sale | Customer Communications
Summary of financial information of segments
Assets held for sale	$ 72.6				$ 297.5				$ 72.6	$ 297.5