Supplemental Cash Flow Information - Net change (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Net change in proceeds managed
Net change in fixed income securities	$ 0	$ 80	$ 234
Net change in short-term investments	592	(451)	(568)
Operating cash flow provided (used)	592	(371)	(334)
Net change in cash	(12)	0	0
Net change in proceeds managed	580	(371)	(334)
Net change in liabilities
Liabilities for collateral, beginning of year	(1,829)	(1,458)	(1,124)
Liabilities for collateral, end of year	(1,249)	(1,829)	(1,458)
Operating cash flow (used) provided	$ (580)	$ 371	$ 334