Variable Interest Entities (Details) $ in Billions	12 Months Ended
	Dec. 31, 2019 USD ($) LimitedPartnerships
Securities limited partnerships and real estate limited partnerships [Member]
Variable Interest Entity [Line Items]
Maximum exposure to loss related to arrangements with variable interest entity	$ 3.4
Number of limited partnerships defined as variable interest entities | LimitedPartnerships	140
Carrying amount of assets	$ 1.8
Commitments to contribute additional cash, amount	$ 1.6
Securities limited partnerships and real estate limited partnerships [Member] | Maximum [Member]
Variable Interest Entity [Line Items]
Ownership percentage	15.00%
Other asset-backed and corporate securities [Member]
Variable Interest Entity [Line Items]
Maximum exposure to loss related to arrangements with variable interest entity	$ 0.7
Carrying amount of assets	$ 0.7
Other asset-backed and corporate securities [Member] | Maximum [Member]
Variable Interest Entity [Line Items]
Ownership percentage
Other various variable interest entities [Member]
Variable Interest Entity [Line Items]
Maximum exposure to loss related to arrangements with variable interest entity
Carrying amount of assets