Consolidated Statements of Cash Flows - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Operating activities
Net income (loss)	$ 353.6	$ 369.2
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Amortization of deferred acquisition costs	52.3	99.6
Additions to deferred acquisition costs	(104.4)	(103.2)
Accrued investment income	(44.6)	(34.7)
Net cash flows for trading securities	109.0	(11.9)
Premiums due and other receivables	(44.1)	124.2
Contractholder and policyholder liabilities and dividends	429.8	617.1
Current and deferred income taxes (benefits)	50.3	57.1
Net realized capital (gains) losses	16.6	(136.6)
Depreciation and amortization expense	48.1	45.8
Real estate acquired through operating activities	(10.7)	(12.8)
Real estate sold through operating activities	0.4	0.1
Stock-based compensation	22.1	22.3
Other	(355.5)	(140.7)
Net adjustments	169.3	526.3
Net cash provided by (used in) operating activities	522.9	895.5
Investing activities
Available-for-sale securities: Purchases	(4,307.0)	(3,558.6)
Available-for-sale securities: Sales	333.7	205.5
Available-for-sale securities: Maturities	2,460.8	1,616.0
Mortgage loans acquired or originated	(473.8)	(475.9)
Mortgage loans sold or repaid	329.3	479.3
Real estate acquired	(90.8)	(44.5)
Real estate sold	47.1	15.0
Net (purchases) sales of property and equipment	(43.8)	(44.2)
Net change in other investments	(86.5)	(45.9)
Net cash provided by (used in) investing activities	(1,831.0)	(1,853.3)
Financing activities
Issuance of common stock	70.8	10.0
Acquisition of treasury stock	(142.8)	(105.6)
Proceeds from financing element derivatives	0.1
Payments for financing element derivatives	(20.9)	(21.3)
Excess tax benefits from share-based payment arrangements		5.0
Purchase of subsidiary shares from noncontrolling interest		(2.3)
Dividends to common stockholders	(130.0)	(110.4)
Issuance of long-term debt		3.2
Net proceeds from (repayments of) short-term borrowings	7.6	(59.9)
Investment contract deposits	2,629.1	3,976.3
Investment contract withdrawals	(2,303.9)	(3,166.3)
Net increase (decrease) in banking operation deposits	6.8	4.0
Other	6.4	3.2
Net cash provided by (used in) financing activities	123.2	535.9
Net increase (decrease) in cash and cash equivalents	(1,184.9)	(421.9)
Cash and cash equivalents at beginning of period	2,719.6	2,564.8
Cash and cash equivalents at end of period	$ 1,534.7	$ 2,142.9