Consolidated Statements Of Cash Flows - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Operating activities
Net income	$ 2,101.4	$ 2,379.1
Adjustments to reconcile net income to net cash provided by operating activities:
Net realized losses (gains) on financial instruments	23.8	(126.9)
Other-than-temporary impairment losses recognized in income	103.6	54.9
Gain on extinguishment of debt	0.0	(1.8)
Loss on disposal of assets	3.5	13.8
Deferred income taxes	81.6	(12.8)
Amortization, net of accretion	601.7	598.6
Depreciation expense	77.7	78.0
Share-based compensation	124.3	111.0
Excess tax benefits from share-based compensation	(48.7)	(92.5)
Changes in operating assets and liabilities:
Receivables, net	(176.2)	454.0
Other invested assets	(17.7)	11.7
Other assets	(925.2)	(616.8)
Policy liabilities	(249.5)	(27.4)
Unearned income	467.9	(166.5)
Accounts payable and accrued expenses	23.3	(303.6)
Other liabilities	381.6	469.3
Income taxes	410.6	363.1
Other, net	(53.9)	(18.3)
Net cash provided by operating activities	2,929.8	3,166.9
Investing activities
Purchases of fixed maturity securities	(7,624.0)	(7,937.8)
Proceeds from fixed maturity securities:
Sales	6,001.0	6,534.5
Maturities, calls and redemptions	979.3	1,017.5
Purchases of equity securities	(1,178.3)	(1,466.9)
Proceeds from sales of equity securities	1,210.4	1,252.4
Purchases of other invested assets	(348.3)	(250.6)
Proceeds from sales of other invested assets	273.1	59.6
Change in collateral and settlement of non-hedging derivatives	(21.0)	27.6
Changes in securities lending collateral	(58.4)	(3.3)
Purchase of subsidiary, net of cash acquired	0.0	(636.2)
Purchases of property and equipment	(415.6)	(408.3)
Proceeds from sales of property and equipment	0.0	35.3
Other, net	(3.0)	(6.0)
Net cash used in investing activities	(1,184.8)	(1,782.2)
Financing activities
Net (repayments of) proceeds from commercial paper borrowings	(177.5)	965.8
Proceeds from long-term borrowings	0.0	1,226.5
Repayments of long-term borrowings	0.0	(2,386.5)
Proceeds from short-term borrowings	1,860.0	2,660.0
Repayments of short-term borrowings	(1,960.0)	(2,520.0)
Changes in securities lending payable	58.4	3.3
Changes in bank overdrafts	311.5	(187.1)
Premiums paid on equity call options	0.0	(16.7)
Proceeds from sale of put options	0.0	16.6
Repurchase and retirement of common stock	0.0	(1,515.8)
Change in collateral and settlements of debt-related derivatives	1,034.0	0.0
Cash dividends	(512.7)	(493.5)
Proceeds from issuance of common stock under employee stock plans	91.2	169.9
Excess tax benefits from share-based compensation	48.7	92.5
Net cash used in financing activities	(1,314.4)	(1,985.0)
Effect of foreign exchange rates on cash and cash equivalents	1.9	(3.6)
Change in cash and cash equivalents	432.5	(603.9)
Cash and cash equivalents at beginning of period	2,113.5	2,151.7
Cash and cash equivalents at end of period	$ 2,546.0	$ 1,547.8