Reinsurance - Business Divestitures Narrative (Details) $ in Millions	12 Months Ended
Dec. 31, 2019 USD ($) reinsurer
Ceded Credit Risk [Line Items]
Number of reinsurer insolvency for making company responsible for administering reinsurance business (at least) \| reinsurer	1
John Hancock
Ceded Credit Risk [Line Items]
Assets held under trust under reinsurance agreement \| $	$ 657.9

Amount of the reinsurer's funds held on its behalf by the ceding insurer, including funds held in trust, under reinsurance treaties or contracts with the assuming insurer as security for the payment of the obligations thereunder.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.2,10)
-URI http://asc.fasb.org/extlink&oid=119400593&loc=d3e572229-122910

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