Consolidated Statements of Cash Flows $ in Millions	12 Months Ended
	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Operating activities
Net income	$ 2,560.0	$ 2,569.7	$ 2,489.7
Adjustments to reconcile net income to net cash provided by operating activities:
Net realized gains on investments	(157.5)	(177.0)	(271.9)
Other-than-temporary impairment losses recognized in income	83.4	49.0	98.9
(Gain) loss on extinguishment of debt	(9.3)	81.1	145.3
(Gain) loss on disposal from discontinued operations	0.0	(3.2)	221.8
Loss (gain) on disposal of assets	16.0	(1.7)	3.9
Deferred income taxes	(65.9)	30.7	59.1
Amortization, net of accretion	802.1	744.5	800.9
Depreciation expense	105.8	106.5	107.9
Impairment of property and equipment	1.8	7.9	47.7
Share-based compensation	148.2	168.9	146.0
Excess tax benefits from share-based compensation	(95.8)	(46.4)	(30.1)
Changes in operating assets and liabilities:
Receivables, net	(42.9)	(1,899.7)	(418.3)
Other invested assets	5.9	(21.7)	(15.1)
Other assets	33.8	405.5	(33.6)
Policy liabilities	193.0	1,240.6	(345.8)
Unearned income	33.9	255.1	(73.8)
Accounts payable and accrued expenses	(219.3)	(14.4)	303.6
Other liabilities	686.4	(7.9)	(154.6)
Income taxes	41.5	(34.0)	9.3
Other, net	(5.1)	(84.2)	(38.6)
Net cash provided by operating activities	4,116.0	3,369.3	3,052.3
Investing activities
Purchases of fixed maturity securities	(9,792.0)	(9,613.4)	(13,704.5)
Proceeds from fixed maturity securities:
Sales	8,909.2	8,066.0	10,977.9
Maturities, calls and redemptions	1,313.6	1,318.7	1,836.8
Purchases of equity securities	(1,561.4)	(912.0)	(820.3)
Proceeds from sales of equity securities	1,471.1	746.5	721.0
Purchases of other invested assets	(505.8)	(205.7)	(251.5)
Proceeds from sales of other invested assets	85.9	124.7	127.1
Settlement of non-hedging derivatives	(36.5)	(67.4)	(109.8)
Changes in securities lending collateral	214.4	(545.6)	(405.1)
Purchases of subsidiaries, net of cash acquired	(638.9)	0.0	0.0
Proceeds from sale of subsidiary, net of cash sold	0.0	740.0	0.0
Purchases of property and equipment	(638.2)	(714.6)	(646.5)
Proceeds from sales of property and equipment	35.3	88.0	39.2
Other, net	(8.2)	(0.1)	1.3
Net cash used in investing activities	(1,151.5)	(974.9)	(2,234.4)
Financing activities
Net proceeds from (repayments of) commercial paper borrowings	682.2	(379.2)	(191.7)
Proceeds from long-term borrowings	1,226.5	2,700.0	1,250.0
Repayments of long-term borrowings	(2,697.2)	(1,730.1)	(1,801.9)
Proceeds from short-term borrowings	2,760.0	2,050.0	1,100.0
Repayments of short-term borrowings	(2,620.0)	(2,050.0)	(950.0)
Changes in securities lending payable	(214.4)	545.6	405.0
Changes in bank overdrafts	(243.8)	173.0	9.9
Premiums paid on equity call options	(16.7)	0.0	(25.8)
Proceeds from sale of put options	16.6	0.0	0.0
Repurchase and retirement of common stock	(1,515.8)	(2,998.8)	(1,620.1)
Cash dividends	(656.6)	(480.7)	(448.0)
Proceeds from issuance of common stock under employee stock plans	186.0	301.3	524.7
Excess tax benefits from share-based compensation	95.8	46.4	30.1
Net cash used in financing activities	(2,997.4)	(1,822.5)	(1,717.8)
Effect of foreign exchange rates on cash and cash equivalents	(5.3)	(7.1)	2.2
Change in cash and cash equivalents	(38.2)	564.8	(897.7)
Cash and cash equivalents at beginning of year	2,151.7	1,586.9	2,484.6
Cash and cash equivalents at end of year	2,113.5	2,151.7	1,586.9
Less cash and cash equivalents of discontinued operations at year end	0.0	0.0	(4.8)
Cash and cash equivalents of continuing operations at end of year	$ 2,113.5	$ 2,151.7	$ 1,582.1