Segment and Geographic Information (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012 segment	Dec. 31, 2011	Dec. 31, 2010
Segment and Geographic Information
Number of operating segments									2
Summary of financial information of segments
Operating revenues	$ 487.0	$ 464.0	$ 465.5	$ 475.9	$ 457.3	$ 433.1	$ 424.1	$ 429.5	$ 1,892.4	$ 1,744.0	$ 1,713.6
Out-of-pocket reimbursements	171.6	168.0	167.3	177.3	166.1	158.3	158.1	162.2	684.2	644.7	614.9
Total revenues (includes related party revenues of $183.4, $192.0 and $202.6)	658.6	632.0	632.8	653.2	623.4	591.4	582.2	591.7	2,576.6	2,388.7	2,328.5
Costs and expenses	559.8	544.4	539.6	559.1	530.6	496.5	477.6	492.3	2,202.9	1,997.0	1,848.5
Depreciation and amortization (including goodwill impairment)	99.6	40.5	42.3	34.0	36.5	33.7	31.3	30.1	216.4	131.6	135.4
Income from operations	(0.8)	47.1	50.9	60.1	56.3	61.2	73.3	69.3	157.3	260.1	344.6
Other income (expense), net	77.2	72.4	194.2	29.7	11.4	(4.5)	14.6	17.2	373.5	38.7	141.7
Equity in earnings (losses) of unconsolidated affiliates	22.4	3.1	1.4	5.3	4.4	1.7	7.2	8.4	32.2	21.7	36.4
Earnings (loss) before interest, income taxes and non-controlling interest									563.0	320.5	522.7
Interest expenses	9.5	10.6	11.7	11.7	11.9	10.9	12.0	11.7	43.5	46.5	46.1
Assets	3,392.5				3,428.6				3,392.5	3,428.6
Financial Services
Summary of financial information of segments
Operating revenues									1,235.6	1,129.6	1,145.8
Intersegment operating revenues									8.4	8.8	10.9
Out-of-pocket reimbursements									54.8	42.1	44.6
Total revenues (includes related party revenues of $183.4, $192.0 and $202.6)									1,298.8	1,180.5	1,201.3
Costs and expenses									997.7	866.1	848.3
Depreciation and amortization (including goodwill impairment)									92.0	76.5	79.4
Income from operations									209.1	237.9	273.6
Other income (expense), net									8.4	6.6	(0.3)
Equity in earnings (losses) of unconsolidated affiliates									27.9	22.0	36.5
Earnings (loss) before interest, income taxes and non-controlling interest									245.4	266.5	309.8
Assets	1,971.1				1,799.5				1,971.1	1,799.5
Customer Communications
Summary of financial information of segments
Operating revenues									642.0	602.1	556.0
Intersegment operating revenues									8.0	7.7	8.1
Out-of-pocket reimbursements									636.7	607.0	575.8
Total revenues (includes related party revenues of $183.4, $192.0 and $202.6)									1,286.7	1,216.8	1,139.9
Costs and expenses									1,214.9	1,148.9	1,013.3
Depreciation and amortization (including goodwill impairment)									107.4	46.7	47.8
Income from operations									(35.6)	21.2	78.8
Other income (expense), net									0.1	0.1	0.7
Equity in earnings (losses) of unconsolidated affiliates									0.5	0.6	0.1
Earnings (loss) before interest, income taxes and non-controlling interest									(35.0)	21.9	79.6
Assets	385.5				476.9				385.5	476.9
Investments and Other
Summary of financial information of segments
Operating revenues									14.8	12.3	11.8
Intersegment operating revenues									44.1	44.0	46.0
Out-of-pocket reimbursements									0.3	1.6	0.4
Total revenues (includes related party revenues of $183.4, $192.0 and $202.6)									59.2	57.9	58.2
Costs and expenses									47.9	38.0	47.3
Depreciation and amortization (including goodwill impairment)									19.6	11.0	10.8
Income from operations									(8.3)	8.9	0.1
Other income (expense), net									365.0	32.0	141.3
Equity in earnings (losses) of unconsolidated affiliates									3.8	(0.9)	(0.2)
Earnings (loss) before interest, income taxes and non-controlling interest									360.5	40.0	141.2
Assets	1,102.3				1,220.8				1,102.3	1,220.8
Elimination Adjustments
Summary of financial information of segments
Intersegment operating revenues									(60.5)	(60.5)	(65.0)
Out-of-pocket reimbursements									(7.6)	(6.0)	(5.9)
Total revenues (includes related party revenues of $183.4, $192.0 and $202.6)									(68.1)	(66.5)	(70.9)
Costs and expenses									(57.6)	(56.0)	(60.4)
Depreciation and amortization (including goodwill impairment)									(2.6)	(2.6)	(2.6)
Income from operations									(7.9)	(7.9)	(7.9)
Earnings (loss) before interest, income taxes and non-controlling interest									(7.9)	(7.9)	(7.9)
Assets	(66.4)				(68.6)				(66.4)	(68.6)
Excluded from segment reporting
Summary of financial information of segments
Interest expenses									$ 43.5	$ 46.5	$ 46.1