Consolidated Balance Sheets (USD $) In Millions, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Current assets:
Cash and cash equivalents	$ 2,185.7	$ 2,484.6
Investments available-for-sale, at fair value:
Fixed maturity securities (amortized cost of $17,271.6 and $16,033.1)	17,538.0	16,912.9
Equity securities (cost of $1,023.5 and $869.9)	1,484.9	1,212.4
Other invested assets, current	15.0	14.8
Accrued investment income	175.4	162.2
Premium and self-funded receivables	4,014.0	3,687.4
Other receivables	1,018.3	928.8
Income taxes receivable	152.3	228.5
Securities lending collateral	837.6	564.6
Deferred tax assets, net	367.9	243.2
Other current assets	1,807.8	1,829.0
Total current assets	29,596.9	28,268.4
Long-term investments available-for-sale, at fair value:
Fixed maturity securities (amortized cost of $442.6 and $426.0)	437.8	431.5
Equity securities (cost of $27.0 and $27.1)	30.3	30.1
Other invested assets, long-term	1,516.8	1,387.7
Property and equipment, net	1,806.5	1,738.3
Goodwill	17,497.6	17,510.5
Other intangible assets	8,921.6	9,102.8
Other noncurrent assets	456.0	486.1
Total assets	60,263.5	58,955.4
Liabilities and shareholders' equity
Medical claims payable	6,117.3	6,174.5
Reserves for future policy benefits	60.2	61.3
Other policyholder liabilities	2,322.6	2,345.7
Total policy liabilities	8,500.1	8,581.5
Unearned income	939.7	896.8
Accounts payable and accrued expenses	3,301.2	3,132.5
Security trades pending payable	284.8	69.3
Securities lending payable	837.7	564.7
Short-term borrowings	350.0	250.0
Current portion of long-term debt	0.1	557.1
Other current liabilities	1,828.8	1,785.0
Total current liabilities	16,042.4	15,836.9
Long-term debt, less current portion	14,514.0	14,170.8
Reserves for future policy benefits, noncurrent	701.9	750.8
Deferred tax liabilities, net	3,322.9	3,381.0
Other noncurrent liabilities	874.2	1,013.2
Total liabilities	35,455.4	35,152.7
Commitment and contingencies-Note 9
Shareholders' equity
Preferred stock, without par value, shares authorized – 100,000,000; shares issued and outstanding – none	0	0
Common stock, par value $0.01, shares authorized – 900,000,000; shares issued and outstanding: 296,188,115 and 304,715,144	3.0	3.0
Additional paid-in capital	10,769.4	10,853.5
Retained earnings	14,040.5	12,647.1
Accumulated other comprehensive (loss) income	(4.8)	299.1
Total shareholders' equity	24,808.1	23,802.7
Total liabilities and shareholders' equity	$ 60,263.5	$ 58,955.4