Reinsurance Reinsurance - Additional Information (Details) $ in Millions	Mar. 31, 2019 USD ($)
Reinsurance
Reinsurance recoverables	$ 9,370
Scottish Re
Reinsurance
Reinsurance recoverables	63
Life contract benefits
Reinsurance
Reinsurance recoverables	$ 796

Amount before valuation allowance recoverable under reinsurance contracts. Examples include, but are not limited to, settled and unsettled claims, incurred but not reported losses, loss adjustment expense, premium paid, policy benefits and policy reserves.

No definition available.

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