Consolidated Balance Sheet - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Statement of Financial Position [Abstract]
Cash and cash equivalents	$ 480.4	$ 314.4
Restricted cash	1,412.1	1,367.6
Premiums and fees receivable	1,734.0	1,462.5
Other current assets	709.3	666.7
Total current assets	4,335.8	3,811.2
Fixed assets - net	202.7	195.4
Deferred income taxes	521.4	392.6
Other noncurrent assets	492.2	385.2
Goodwill - net	3,662.9	3,449.6
Amortizable intangible assets - net	1,698.8	1,776.0
Total assets	10,913.8	10,010.0
Premiums payable to insurance and reinsurance companies	2,877.1	2,623.3
Accrued compensation and other accrued liabilities	812.7	623.7
Unearned fees	61.3	66.1
Other current liabilities	58.6	61.7
Premium financing borrowings	137.0	127.9
Corporate related borrowings - current	245.0	140.0
Total current liabilities	4,191.7	3,642.7
Corporate related borrowings - noncurrent	2,075.0	2,125.0
Other noncurrent liabilities	958.9	937.2
Total liabilities	7,225.6	6,704.9
Stockholders' equity:
Common stock - authorized 400.0 shares; issued and outstanding 176.9 shares in 2015 and 164.6 shares in 2014	176.9	164.6
Capital in excess of par value	3,209.4	2,649.4
Retained earnings	774.5	676.0
Accumulated other comprehensive loss	(522.5)	(260.6)
Stockholders' equity attributable to controlling interests	3,638.3	3,229.4
Stockholders' equity attributable to noncontrolling interests	49.9	75.7
Total stockholders' equity	3,688.2	3,305.1
Total liabilities and stockholders' equity	$ 10,913.8	$ 10,010.0