Consolidated Statements Of Cash Flows (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011
Operating:
Net income	$ 100.1	$ 98.1
Adjustments to reconcile net income to net cash provided by operating activities:
Net realized capital losses	6.8	7.9
Depreciation and amortization	87.8	90.2
Deferral of acquisition costs, value of business acquired and other intangible assets, net	(55.3)	(64.6)
Deferred income taxes	8.5	(2.9)
Changes in other assets and liabilities:
Receivables and accrued income	(24.7)	(26.7)
Future policy benefits and claims	111.1	114.0
Other, net	84.0	29.8
Net cash provided by operating activities	318.3	245.8
Investing:
Proceeds from sale, maturity, or repayment of fixed maturity securities-available-for-sale	638.6	694.2
Proceeds from sale or repayment of commercial mortgage loans	588.1	424.5
Proceeds from sale of real estate	7.0	53.4
Acquisition of fixed maturity securities-available-for-sale	(846.8)	(847.5)
Acquisition or origination of commercial mortgage loans	(861.6)	(752.9)
Acquisition of real estate	(0.9)	(3.8)
Acquisition of other invested assets	(37.2)	(36.6)
Acquisition of property and equipment, net	(11.8)	(12.6)
Net cash used in investing activities	(524.6)	(481.3)
Financing:
Policyholder fund deposits	1,401.8	1,395.2
Policyholder fund withdrawals	(1,155.4)	(1,053.8)
Repayment of senior debt	(250.0)	0
Issuance of debt, net of issuance costs	246.7	0
Issuance of common stock	6.7	6.3
Repurchases of common stock	(10.0)	(90.0)
Other financing activity, net	0.5	(2.0)
Net cash provided by financing activities	240.3	255.7
Increase in cash and cash equivalents	34.0	20.2
Cash and cash equivalents, beginning of period	138.4	152.0
Cash and cash equivalents, end of period	172.4	172.2
Cash Paid During Period For [Abstract]
Interest	151.4	147.7
Income taxes	0.9	59.6
Non-cash transactions:
Real estate acquired through commercial mortgage loan foreclosure	14.3	13.0
Commercial mortgage loans originated on real estate sold	$ 0.8	$ 27.8