Deferred Policy Acquisition Costs (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Deferred Policy Acquisition Cost [Line Items]
Balance, beginning of period	$ 789	$ 785	$ 670
Deferred costs	1,751	1,666	1,635
Amortization — DAC	(1,680)	(1,706)	(1,622)
Balance, end of period	881	789	785
Disposal Group, Disposed of by Sale, Not Discontinued Operations [Member] | Continental Europe Operations [Member]
Deferred Policy Acquisition Cost [Line Items]
DAC transferred to assets held for sale	0	(3)	0
The Navigators Group, Inc. [Member] | Customer relationships
Deferred Policy Acquisition Cost [Line Items]
Add back amortization of value of business acquired [1]	$ 21	$ 47	$ 102