Consolidated Statements of Cash Flows (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Operating activities
Net income (loss)	$ 751.2	$ 717.2	$ 645.7
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Amortization of deferred policy acquisition costs	538.0	205.9	92.2
Additions to deferred policy acquisition costs	(520.5)	(496.3)	(482.4)
Accrued investment income	50.9	25.8	58.8
Net cash flows for trading securities	110.8	188.3	(127.4)
Premiums due and other receivables	(220.4)	(9.6)	(126.9)
Contractholder and policyholder liabilities and dividends	1,090.7	1,384.2	1,530.9
Current and deferred income taxes (benefits)	51.3	60.9	65.7
Net realized capital (gains) losses	122.3	191.5	398.3
Depreciation and amortization expense	115.8	164.7	138.5
Mortgage loans held for sale, acquired or originated	(132.3)	(60.6)	(61.2)
Mortgage loans held for sale, sold or repaid, net of gain	82.0	61.2	75.4
Real estate acquired through operating activities	(37.4)		(19.8)
Real estate sold through operating activities	141.8	121.6	5.2
Stock-based compensation	43.4	47.6	37.2
Other	525.7	189.3	12.8
Net adjustments	1,962.1	2,074.5	1,597.3
Net cash provided by (used in) operating activities	2,713.3	2,791.7	2,243.0
Investing activities
Available-for-sale securities: Purchases	(6,742.4)	(7,187.9)	(7,933.3)
Available-for-sale securities: Sales	980.7	1,684.6	3,439.8
Available-for-sale securities: Maturities	5,760.8	5,161.3	4,568.1
Mortgage loans acquired or originated	(1,484.9)	(1,272.0)	(586.5)
Mortgage loans sold or repaid	1,793.1	1,798.0	1,704.4
Real estate acquired	(129.9)	(53.8)	(62.2)
Net (purchases) sales of property and equipment	(56.9)	(21.5)	(26.2)
Purchases of interest in subsidiaries, net of cash acquired	(270.5)		(45.7)
Net change in other investments	(52.1)	(81.2)	(31.6)
Net cash provided by (used in) investing activities	(202.1)	27.5	1,026.8
Financing activities
Issuance of common stock	25.9	20.6	1,123.0
Acquisition of treasury stock	(556.4)	(2.6)	(4.1)
Proceeds from financing element derivatives	75.9	79.3	122.0
Payments for financing element derivatives	(46.5)	(46.5)	(67.4)
Excess tax benefits from share-based payment arrangements	2.0	1.0	0.2
Dividends to common stockholders	(213.7)	(176.2)	(159.5)
Dividends to preferred stockholders	(33.0)	(33.0)	(33.0)
Issuance of long-term debt		2.3	745.1
Principal repayments of long-term debt	(12.2)	(11.1)	(468.2)
Net proceeds from (repayments of) short-term borrowings	3.2	1.7	(405.1)
Investment contract deposits	6,302.1	4,283.8	4,224.1
Investment contract withdrawals	(7,079.0)	(7,343.4)	(8,752.7)
Net increase (decrease) in banking operation deposits	(18.5)	46.2	43.9
Other	(4.5)	(4.3)	(5.7)
Net cash provided by (used in) financing activities	(1,554.7)	(3,182.2)	(3,637.4)
Net increase (decrease) in cash and cash equivalents	956.5	(363.0)	(367.6)
Cash and cash equivalents at beginning of period	1,877.4	2,240.4	2,608.0
Cash and cash equivalents at end of period	2,833.9	1,877.4	2,240.4
Supplemental Information:
Cash paid for interest	154.1	123.4	129.9
Cash paid for income taxes	$ 152.8	$ 55.2	$ 75.4