Deferred Policy Acquisition and Sales Inducement Costs -Deferred policy acquisition costs activity (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Deferred policy acquisition costs activity
Balance, beginning of year	$ 4,699	$ 4,784	$ 4,191
Acquisition costs deferred	5,758	5,622	5,663
Amortization charged to income	(5,630)	(5,533)	(5,222)
Effect of unrealized gains and losses	(127)	(174)	152
Balance, end of year	$ 4,700	$ 4,699	$ 4,784