INVESTMENTS - Debt Securities in HTM in Unrecognized Loss Position (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Fair value
Less than 12 months		$ 13,566
12 months or longer		3,006
Total		16,572
Gross unrecognized losses
Less than 12 months		23
12 months or longer		86
Total		109
Unrealized loss, other than temporary impairment, not credit loss, recorded in AOCI	$ (582)
Mortgage-backed securities
Fair value
Less than 12 months		3,590
12 months or longer		1,116
Total		4,706
Gross unrecognized losses
Less than 12 months		10
12 months or longer		11
Total		21
State and municipal
Fair value
Less than 12 months		34
12 months or longer		1,125
Total		1,159
Gross unrecognized losses
Less than 12 months		1
12 months or longer		27
Total		28
Foreign government
Fair value
Less than 12 months		1,970
12 months or longer		0
Total		1,970
Gross unrecognized losses
Less than 12 months		1
12 months or longer		0
Total		1
Asset-backed securities
Fair value
Less than 12 months		7,972
12 months or longer		765
Total		8,737
Gross unrecognized losses
Less than 12 months		11
12 months or longer		48
Total		$ 59