Condensed Consolidated Statement of Income (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Operating revenues	$ 485.1	$ 465.5	$ 980.3	$ 941.4
Out-of-pocket reimbursements	172.0	167.3	359.2	344.6
Total revenues	657.1	632.8	1,339.5	1,286.0
Costs and expenses	551.3	539.6	1,125.9	1,098.7
Depreciation and amortization	33.1	42.3	66.3	76.3
Income from operations	72.7	50.9	147.3	111.0
Interest expense	(9.3)	(11.7)	(18.9)	(23.4)
Other income, net	28.4	194.2	101.6	223.9
Equity in earnings of unconsolidated affiliates	9.5	1.4	15.1	6.7
Income before income taxes	101.3	234.8	245.1	318.2
Income taxes	22.8	89.9	73.4	118.0
Net income	$ 78.5	$ 144.9	$ 171.7	$ 200.2
Average common shares outstanding (in shares)	43.7	45.0	44.0	44.7
Average diluted shares outstanding (in shares)	44.5	45.7	45.0	45.5
Basic earnings per share (in dollars per share)	$ 1.80	$ 3.22	$ 3.90	$ 4.48
Diluted earnings per share (in dollars per share)	$ 1.77	$ 3.17	$ 3.81	$ 4.40
Cash dividends per share of common stock (in dollars per share)	$ 0.3	$ 0	$ 0.6	$ 0.4