Commitments and Contingencies Level 4 - Unfunded Commitments (Details)	Dec. 31, 2018 USD ($)
Other Commitments [Abstract]
Other Commitment	$ 577,000,000
Commitments to Fund Limited Partnership and Other Alternative Investments	478,000,000
Commitment to fund Private placement securities	42,000,000
Commitments to Fund Mortgage Loans	57,000,000
Commitments to Fund Mortgage Loans, Amount the Company Can Cancel	$ 18

Minimum amount of other commitment not otherwise specified in the taxonomy. Excludes commitments explicitly modeled in the taxonomy, including but not limited to, long-term and short-term purchase commitments, recorded and unrecorded purchase obligations, supply commitments, registration payment arrangements, leases, debt, product warranties, guarantees, environmental remediation obligations, and pensions.

No definition available.

Name:	us-gaap_OtherCommitment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant