VOBA and Other Intangible Assets (Information About VOBA) (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Movement in Present Value of Future Insurance Profits [Roll Forward]
Beginning balance	$ 3,157.8	$ 24.4	$ 32.1
Additions	(4.0)	3,972.6	0.0
Amortization, net of interest accrued	(1,127.4)	(825.2)	(7.9)
Foreign currency translation and other	(22.1)	(14.0)	0.2
Ending balance	$ 2,004.3	$ 3,157.8	$ 24.4

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

No definition available.

Name:	us-gaap_MovementInPresentValueOfFutureInsuranceProfitsRollForward
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of addition for present value of future profits of insurance contract acquired in business combination.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 20
-Section S99
-Paragraph 2
-Subparagraph (2)
-URI http://asc.fasb.org/extlink&oid=27015749&loc=d3e569990-122904

+ Details

Name:	us-gaap_PresentValueOfFutureInsuranceProfitsAdditionsFromAcquisitions
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of amortization expense (reversal of expense) for present value of future profits of insurance contract acquired in business combination.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3602-108585

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 50
-Paragraph 2
-Subparagraph (a)(2)
-URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16323-109275

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 20
-Section S99
-Paragraph 2
-Subparagraph 2
-URI http://asc.fasb.org/extlink&oid=27015749&loc=d3e569990-122904

+ Details

Name:	us-gaap_PresentValueOfFutureInsuranceProfitsAmortizationExpense1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of foreign currency translation gain (loss) which increases (decreases) present value of future profits of insurance contract acquired in business combination.

+ References

No definition available.

+ Details

Name:	us-gaap_PresentValueOfFutureInsuranceProfitsForeignCurrencyTranslationGainLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount, after accumulated amortization, of present value of future profits of insurance contract acquired in business combination.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 20
-Section S99
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=27015749&loc=d3e569990-122904

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.10)
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

+ Details

Name:	us-gaap_ValueOfBusinessAcquiredVOBA
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant