Investments (Details 10) (USD $) In Millions, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011	Mar. 31, 2011
Mortgage loan non-accrual and aging disclosures
Mortgage loans, Non-accrual status	$ 81.6	$ 75.7
30-59 days past due	33.6	85.0
60-89 days past due	7.8	13.0
90 days or more past due	32.0	50.9
Total past due	73.4	148.9
Current	11,324.8	10,680.4
Mortgage loans, Total amortized cost	11,398.2	10,829.3	11,024.7
Recorded investment 90 days or more past due and accruing	8.5	7.5
Commercial mortgage loans
Mortgage loan non-accrual and aging disclosures
Mortgage loans, Total amortized cost	10,016.8	9,461.4	9,515.5
Brick and mortar
Mortgage loan non-accrual and aging disclosures
Mortgage loans, Non-accrual status	53.5	46.8
30-59 days past due	4.4	61.4
60-89 days past due		4.4
90 days or more past due	4.0	22.5
Total past due	8.4	88.3
Current	9,433.0	8,803.5
Mortgage loans, Total amortized cost	9,441.4	8,891.8
Credit tenant loans
Mortgage loan non-accrual and aging disclosures
Current	575.4	569.6
Mortgage loans, Total amortized cost	575.4	569.6
Residential mortgage loans
Mortgage loan non-accrual and aging disclosures
Mortgage loans, Total amortized cost	1,381.4	1,367.9	1,509.2
Home equity
Mortgage loan non-accrual and aging disclosures
Mortgage loans, Non-accrual status	12.2	13.2
30-59 days past due	5.8	7.8
60-89 days past due	2.2	2.6
90 days or more past due	4.9	6.2
Total past due	12.9	16.6
Current	570.2	594.4
Mortgage loans, Total amortized cost	583.1	611.0
First liens
Mortgage loan non-accrual and aging disclosures
Mortgage loans, Non-accrual status	15.9	15.7
30-59 days past due	23.4	15.8
60-89 days past due	5.6	6.0
90 days or more past due	23.1	22.2
Total past due	52.1	44.0
Current	746.2	712.9
Mortgage loans, Total amortized cost	798.3	756.9
Recorded investment 90 days or more past due and accruing	$ 8.5	$ 7.5

Financing receivables that are less than 30 days past due.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 7A

-URI http://asc.fasb.org/extlink&oid=6965416&loc=SL6953401-111524

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Financing receivables that are less than 60 days past due but more than 29 days past due.

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Financing receivables that are less than 90 days past due but more than 59 days past due.

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Recorded investment in financing receivables that are 90 days or more past due and still accruing.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 7

-URI http://asc.fasb.org/extlink&oid=6965416&loc=d3e5111-111524

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Financing receivables that are equal to or greater than 90 days past due.

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For an unclassified balance sheet, an amount representing an agreement for an unconditional promise by the maker to pay the Company (holder) a definite sum of money at a future date(s). Such amount may include accrued interest receivable in accordance with the terms of the note. The note also may contain provisions and related items including a discount or premium, payable on demand, secured, or unsecured, interest bearing or noninterest bearing, among a myriad of other features and characteristics. This amount does not include amounts related to receivables held-for-sale.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.10(3))

-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Article 9

-Section 03

-Paragraph 10

-Subparagraph 3

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