Consolidated Statements Of Cash Flows (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012
Operating activities
Net income	$ 2,341.5	$ 2,191.3
Adjustments to reconcile net income to net cash provided by operating activities:
Net realized gains on investments	(166.4)	(232.0)
Other-than-temporary impairment losses recognized in income	73.1	20.6
Loss on extinguishment of debt	145.3	0
Loss on disposal of assets	5.1	1.6
Deferred income taxes	(12.0)	255.3
Amortization, net of accretion	592.7	474.8
Depreciation expense	78.4	72.8
Share-based compensation	103.7	123.7
Excess tax benefits from share-based compensation	(23.5)	(23.2)
Changes in operating assets and liabilities, net of effect of business combinations:
Receivables, net	(368.0)	(133.2)
Other invested assets	1.7	(26.6)
Other assets	51.6	(33.3)
Policy liabilities	(130.3)	(16.8)
Unearned income	42.9	(102.8)
Accounts payable and accrued expenses	95.9	(446.7)
Other liabilities	(78.0)	(57.5)
Income taxes	87.5	(79.5)
Other, net	(61.7)	(3.7)
Net cash provided by operating activities	2,779.5	1,984.8
Investing activities
Purchases of fixed maturity securities	(11,494.1)	(11,808.8)
Proceeds from fixed maturity securities:
Sales	8,756.4	8,433.4
Maturities, calls and redemptions	1,490.0	1,347.8
Purchases of equity securities	(574.4)	(245.1)
Proceeds from sales of equity securities	575.2	312.3
Purchases of other invested assets	(207.9)	(153.7)
Proceeds from sales of other invested assets	53.0	25.4
Changes in securities lending collateral	(273.1)	171.5
Purchases of subsidiaries, net of cash acquired	0	(992.3)
Purchases of property and equipment	(408.1)	(375.1)
Proceeds from sales of property and equipment	0	0.4
Other, net	(3.8)	(0.9)
Net cash used in investing activities	(2,086.8)	(3,285.1)
Financing activities
Net proceeds from commercial paper borrowings	224.1	30.1
Proceeds from long-term borrowings	1,250.0	4,935.2
Repayments of long-term borrowings	(1,801.9)	(1,251.2)
Proceeds from short-term borrowings	600.0	392.0
Repayments of short-term borrowings	(500.0)	(300.0)
Changes in securities lending payable	273.0	(171.5)
Changes in bank overdrafts	72.3	(94.6)
Repurchase and retirement of common stock	(1,170.4)	(1,828.8)
Cash dividends	(337.5)	(280.0)
Proceeds from issuance of common stock under employee stock plans	374.9	86.7
Excess tax benefits from share-based compensation	23.5	23.2
Net cash (used in) provided by financing activities	(992.0)	1,541.1
Effect of foreign exchange rates on cash and cash equivalents	0.4	(0.3)
Change in cash and cash equivalents	(298.9)	240.5
Cash and cash equivalents at beginning of period	2,484.6	2,201.6
Cash and cash equivalents at end of period	$ 2,185.7	$ 2,442.1