Segment Information (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended			6 Months Ended	9 Months Ended		12 Months Ended
	Sep. 30, 2013	Mar. 31, 2013 segment	Sep. 30, 2012	Sep. 30, 2013 segment	Sep. 30, 2013 segment	Sep. 30, 2012	Dec. 31, 2012	Dec. 31, 2011
Segment Reporting [Abstract]
Number of operating segments		2		3	3
Summary of financial information of segments
Assets	$ 3,103.3			$ 3,103.3	$ 3,103.3		$ 3,392.5
Operating revenues	480.2		464.0		1,460.5	1,405.4	1,892.4	1,744.0
Intersegment operating revenues	0		0		0	0	0	0
Out-of-pocket reimbursements	171.6		168.0		530.8	512.6	684.2	644.7
Total revenues	651.8		632.0		1,991.3	1,918.0	2,576.6	2,388.7
Costs and expenses	531.4		544.4		1,657.3	1,643.1	2,202.9	1,997.0
Depreciation and amortization	34.1		40.5		100.4	116.8	216.4	131.6
Income from operations	86.3		47.1		233.6	158.1	157.3	260.1
Other income (loss), net	73.4		72.4		175.0	296.3	373.5	38.7
Equity in earnings of unconsolidated affiliates	3.8		3.1		18.9	9.8	32.2	21.7
Earnings (loss) before interest and income taxes	163.5		122.6		427.5	464.2	563.0	320.5
Interest expense	8.4		10.6		27.3	34.0	(43.5)	(46.5)
Financial Services
Summary of financial information of segments
Assets	1,407.3			1,407.3	1,407.3		1,589.0
Operating revenues	237.1		231.4		713.5	695.2	935.0	858.8
Intersegment operating revenues	11.7		10.8		32.8	32.4	43.6	40.4
Out-of-pocket reimbursements	8.8		11.7		31.9	36.6	49.7	36.8
Total revenues	257.6		253.9		778.2	764.2	1,028.3	936.0
Costs and expenses	187.0		189.9		577.2	573.1	777.0	657.2
Depreciation and amortization	16.2		17.4		47.5	56.7	74.3	56.9
Income from operations	54.4		46.6		153.5	134.4	177.0	221.9
Other income (loss), net	2.6		7.3		0	12.7	8.1	8.0
Equity in earnings of unconsolidated affiliates	2.5		0.7		14.1	6.0	27.6	22.0
Earnings (loss) before interest and income taxes	59.5		54.6		167.6	153.1	212.7	251.9
Healthcare Services
Summary of financial information of segments
Assets	310.3			310.3	310.3		382.1
Operating revenues	80.7		71.2		242.7	221.9	300.6	270.8
Intersegment operating revenues	0		0		0	0	0	0
Out-of-pocket reimbursements	1.5		1.2		4.2	3.9	5.1	5.3
Total revenues	82.2		72.4		246.9	225.8	305.7	276.1
Costs and expenses	66.0		62.7		202.8	194.1	255.9	240.5
Depreciation and amortization	4.8		4.3		14.2	13.2	17.7	19.6
Income from operations	11.4		5.4		29.9	18.5	32.1	16.0
Other income (loss), net	0.1		0.1		0.2	0.3	0.3	(1.4)
Equity in earnings of unconsolidated affiliates	0.1		0.1		0.3	0.2	0.3	0
Earnings (loss) before interest and income taxes	11.6		5.6		30.4	19.0	32.7	14.6
Customer Communications
Summary of financial information of segments
Assets	434.8			434.8	434.8		385.5
Operating revenues	158.8		157.7		492.8	477.6	642.0	602.1
Intersegment operating revenues	1.7		1.9		5.7	6.1	8.0	7.7
Out-of-pocket reimbursements	163.1		156.9		500.2	477.7	636.7	607.0
Total revenues	323.6		316.5		998.7	961.4	1,286.7	1,216.8
Costs and expenses	297.2		294.7		923.0	905.7	1,214.9	1,148.9
Depreciation and amortization	10.9		11.2		32.7	33.3	107.4	46.7
Income from operations	15.5		10.6		43.0	22.4	(35.6)	21.2
Other income (loss), net	0.5		0		0.2	0	0.1	0.1
Equity in earnings of unconsolidated affiliates	0.2		0.1		0.3	0.3	0.5	0.6
Earnings (loss) before interest and income taxes	16.2		10.7		43.5	22.7	(35.0)	21.9
Investments and Other
Summary of financial information of segments
Assets	1,014.4			1,014.4	1,014.4		1,102.3
Operating revenues	3.6		3.7		11.5	10.7	14.8	12.3
Intersegment operating revenues	11.0		11.4		31.8	33.9	44.1	44.0
Out-of-pocket reimbursements	0.1		0.1		0.1	0.2	0.3	1.6
Total revenues	14.7		15.2		43.4	44.8	59.2	57.9
Costs and expenses	4.6		20.6		22.1	40.6	47.9	38.0
Depreciation and amortization	2.9		8.2		8.0	15.5	19.6	11.0
Income from operations	7.2		(13.6)		13.3	(11.3)	(8.3)	8.9
Other income (loss), net	70.2		65.0		174.6	283.3	365.0	32.0
Equity in earnings of unconsolidated affiliates	1.0		2.2		4.2	3.3	3.8	(0.9)
Earnings (loss) before interest and income taxes	78.4		53.6		192.1	275.3	360.5	40.0
Elimination Adjustments
Summary of financial information of segments
Assets	(63.5)			(63.5)	(63.5)		(66.4)
Operating revenues	0		0		0	0	0	0
Intersegment operating revenues	(24.4)		(24.1)		(70.3)	(72.4)	(95.7)	(92.1)
Out-of-pocket reimbursements	(1.9)		(1.9)		(5.6)	(5.8)	(7.6)	(6.0)
Total revenues	(26.3)		(26.0)		(75.9)	(78.2)	(103.3)	(98.1)
Costs and expenses	(23.4)		(23.5)		(67.8)	(70.4)	(92.8)	(87.6)
Depreciation and amortization	(0.7)		(0.6)		(2.0)	(1.9)	(2.6)	(2.6)
Income from operations	(2.2)		(1.9)		(6.1)	(5.9)	(7.9)	(7.9)
Other income (loss), net	0		0		0	0	0	0
Equity in earnings of unconsolidated affiliates	0		0		0	0	0	0
Earnings (loss) before interest and income taxes	$ (2.2)		$ (1.9)		$ (6.1)	$ (5.9)	$ (7.9)	$ (7.9)