Consolidated Statements of Cash Flows - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
Operating activities
Net income (loss)	$ 696.2	$ 694.0
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Amortization of deferred acquisition costs	171.6	101.6
Additions to deferred acquisition costs	(201.5)	(191.9)
Accrued investment income	(17.4)	7.2
Net cash flows for trading securities	(41.1)	(33.3)
Premiums due and other receivables	57.7	(48.2)
Contractholder and policyholder liabilities and dividends	1,314.0	1,546.2
Current and deferred income taxes (benefits)	110.9	(75.4)
Net realized capital (gains) losses	(170.3)	48.4
Depreciation and amortization expense	93.2	83.3
Real estate acquired through operating activities	(21.9)	(29.3)
Real estate sold through operating activities	21.0	51.6
Stock-based compensation	40.1	50.3
Other	73.1	(87.1)
Net adjustments	1,429.4	1,423.4
Net cash provided by (used in) operating activities	2,125.6	2,117.4
Investing activities
Available-for-sale securities: Purchases	(7,476.9)	(4,828.5)
Available-for-sale securities: Sales	557.4	983.1
Available-for-sale securities: Maturities	3,667.9	3,636.1
Mortgage loans acquired or originated	(1,198.0)	(1,057.1)
Mortgage loans sold or repaid	910.4	775.3
Real estate acquired	(66.4)	(204.1)
Net (purchases) sales of property and equipment	(74.7)	(67.3)
Net change in other investments	6.3	(174.6)
Net cash provided by (used in) investing activities	(3,674.0)	(937.1)
Financing activities
Issuance of common stock	11.2	29.6
Acquisition of treasury stock	(209.7)	(75.6)
Proceeds from financing element derivatives	0.2	0.2
Payments for financing element derivatives	(43.0)	(39.5)
Excess tax benefits from share-based payment arrangements	5.5	14.1
Purchase of subsidiary shares from noncontrolling interest	(2.3)	(11.0)
Dividends to common stockholders	(223.2)	(218.3)
Dividends to preferred stockholders		(16.5)
Preferred stock redemption		(550.0)
Issuance of long-term debt	3.7	797.4
Principal repayments of long-term debt		(19.8)
Net proceeds from (repayments of) short-term borrowings	(156.9)
Investment contract deposits	6,877.7	2,722.9
Investment contract withdrawals	(5,071.0)	(3,414.7)
Net increase (decrease) in banking operation deposits	47.1	8.2
Other	(0.3)	(6.8)
Net cash provided by (used in) financing activities	1,239.0	(779.8)
Net increase (decrease) in cash and cash equivalents	(309.4)	400.5
Cash and cash equivalents at beginning of period	2,564.8	1,863.9
Cash and cash equivalents at end of period	$ 2,255.4	$ 2,264.4