FAIR VALUE MEASUREMENTS - Fair Value Measurement Inputs and Valuation Techniques (Details) $ in Millions		Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Fair Value Measurement Inputs and Valuation Technique
Available for sale, fixed maturity securities		$ 98,696	$ 105,882
Equity securities		1,603	1,283
Asset derivatives		936	583
Liability derivatives		1,619	697
Assets, fair value		108,012	114,028
Liabilities, fair value		1,619	697
Level 3
Fair Value Measurement Inputs and Valuation Technique
Available for sale, fixed maturity securities		1,298	1,017
Equity securities		173	102
Asset derivatives		0	133
Assets, fair value		1,471	1,252
Liabilities, fair value		0	231
Net asset value valuation technique
Fair Value Measurement Inputs and Valuation Technique
Equity securities		173	102
Net asset value valuation technique | Level 3
Fair Value Measurement Inputs and Valuation Technique
Equity securities		173	102
Foreign currency swaps
Fair Value Measurement Inputs and Valuation Technique
Asset derivatives		137	180
Liability derivatives		427	312
Foreign currency swaps | Level 3
Fair Value Measurement Inputs and Valuation Technique
Asset derivatives		0	133
Liability derivatives		0	231
Foreign currency swaps | Fair Value, Unobservable Input, Interest Rates (USD), Interest Rates (JPY), and CDS Spreads | Discounted cash flow technique | Level 3
Fair Value Measurement Inputs and Valuation Technique
Asset derivatives			69
Liability derivatives			160
Foreign currency swaps | Fair Value, Unobservable Input, Interest Rates (USD) and Interest Rates (JPY) | Discounted cash flow technique | Level 3
Fair Value Measurement Inputs and Valuation Technique
Asset derivatives			64
Liability derivatives			$ 71
Foreign currency swaps | Credit Spread | Fair Value, Unobservable Input, Interest Rates (USD), Interest Rates (JPY), and CDS Spreads | Lower Limit | Level 3
Fair Value Measurement Inputs and Valuation Technique
Derivative asset, measurement input			0.0022
Derivative liability, measurement input			0.0041
Foreign currency swaps | Credit Spread | Fair Value, Unobservable Input, Interest Rates (USD), Interest Rates (JPY), and CDS Spreads | Upper Limit | Level 3
Fair Value Measurement Inputs and Valuation Technique
Derivative asset, measurement input			0.0128
Derivative liability, measurement input			0.0140
Dollar-denominated
Fair Value Measurement Inputs and Valuation Technique
Available for sale, fixed maturity securities		40,709	$ 41,611
Equity securities		817	$ 603
Dollar-denominated | Foreign currency swaps | Discount Rate | Fair Value, Unobservable Input, Interest Rates (USD), Interest Rates (JPY), and CDS Spreads | Lower Limit | Level 3
Fair Value Measurement Inputs and Valuation Technique
Derivative asset, measurement input	[1]		0.0093
Derivative liability, measurement input	[1]		0.0093
Dollar-denominated | Foreign currency swaps | Discount Rate | Fair Value, Unobservable Input, Interest Rates (USD), Interest Rates (JPY), and CDS Spreads | Upper Limit | Level 3
Fair Value Measurement Inputs and Valuation Technique
Derivative asset, measurement input	[1]		0.0140
Derivative liability, measurement input	[1]		0.0112
Dollar-denominated | Foreign currency swaps | Discount Rate | Fair Value, Unobservable Input, Interest Rates (USD) and Interest Rates (JPY) | Lower Limit | Level 3
Fair Value Measurement Inputs and Valuation Technique
Derivative asset, measurement input	[1]		0.0093
Derivative liability, measurement input	[1]		0.0093
Dollar-denominated | Foreign currency swaps | Discount Rate | Fair Value, Unobservable Input, Interest Rates (USD) and Interest Rates (JPY) | Upper Limit | Level 3
Fair Value Measurement Inputs and Valuation Technique
Derivative asset, measurement input	[1]		0.0140
Derivative liability, measurement input	[1]		0.0112
Yen-denominated
Fair Value Measurement Inputs and Valuation Technique
Available for sale, fixed maturity securities		57,987	$ 64,271
Equity securities		744	$ 680
Yen-denominated | Foreign currency swaps | Discount Rate | Fair Value, Unobservable Input, Interest Rates (USD), Interest Rates (JPY), and CDS Spreads | Lower Limit | Level 3
Fair Value Measurement Inputs and Valuation Technique
Derivative asset, measurement input	[2]		0.0005
Derivative liability, measurement input	[2]		0.0005
Yen-denominated | Foreign currency swaps | Discount Rate | Fair Value, Unobservable Input, Interest Rates (USD), Interest Rates (JPY), and CDS Spreads | Upper Limit | Level 3
Fair Value Measurement Inputs and Valuation Technique
Derivative asset, measurement input	[2]		0.0043
Derivative liability, measurement input	[2]		0.0035
Yen-denominated | Foreign currency swaps | Discount Rate | Fair Value, Unobservable Input, Interest Rates (USD) and Interest Rates (JPY) | Lower Limit | Level 3
Fair Value Measurement Inputs and Valuation Technique
Derivative asset, measurement input	[2]		0.0005
Derivative liability, measurement input	[2]		0.0005
Yen-denominated | Foreign currency swaps | Discount Rate | Fair Value, Unobservable Input, Interest Rates (USD) and Interest Rates (JPY) | Upper Limit | Level 3
Fair Value Measurement Inputs and Valuation Technique
Derivative asset, measurement input	[2]		0.0043
Derivative liability, measurement input	[2]		0.0035
Mortgage- and asset-backed securities
Fair Value Measurement Inputs and Valuation Technique
Available for sale, fixed maturity securities		1,246	$ 1,038
Mortgage- and asset-backed securities | Level 3
Fair Value Measurement Inputs and Valuation Technique
Available for sale, fixed maturity securities		291	224
Mortgage- and asset-backed securities | Consensus pricing valuation technique
Fair Value Measurement Inputs and Valuation Technique
Available for sale, fixed maturity securities		291	674
Mortgage- and asset-backed securities | Consensus pricing valuation technique | Level 3
Fair Value Measurement Inputs and Valuation Technique
Available for sale, fixed maturity securities		291	224
Mortgage- and asset-backed securities | Dollar-denominated
Fair Value Measurement Inputs and Valuation Technique
Available for sale, fixed maturity securities		928	670
Mortgage- and asset-backed securities | Yen-denominated
Fair Value Measurement Inputs and Valuation Technique
Available for sale, fixed maturity securities		318	368
Banks/financial institutions
Fair Value Measurement Inputs and Valuation Technique
Available for sale, fixed maturity securities		11,591	12,060
Banks/financial institutions | Level 3
Fair Value Measurement Inputs and Valuation Technique
Available for sale, fixed maturity securities		45	24
Banks/financial institutions | Consensus pricing valuation technique
Fair Value Measurement Inputs and Valuation Technique
Available for sale, fixed maturity securities		45	24
Banks/financial institutions | Consensus pricing valuation technique | Level 3
Fair Value Measurement Inputs and Valuation Technique
Available for sale, fixed maturity securities		45	24
Banks/financial institutions | Dollar-denominated
Fair Value Measurement Inputs and Valuation Technique
Available for sale, fixed maturity securities		3,913	3,724
Banks/financial institutions | Yen-denominated
Fair Value Measurement Inputs and Valuation Technique
Available for sale, fixed maturity securities		7,678	8,336
Public utilities
Fair Value Measurement Inputs and Valuation Technique
Available for sale, fixed maturity securities		10,051	10,817
Public utilities | Level 3
Fair Value Measurement Inputs and Valuation Technique
Available for sale, fixed maturity securities		493	422
Public utilities | Discounted cash flow technique
Fair Value Measurement Inputs and Valuation Technique
Available for sale, fixed maturity securities		493	422
Public utilities | Discounted cash flow technique | Level 3
Fair Value Measurement Inputs and Valuation Technique
Available for sale, fixed maturity securities		493	422
Public utilities | Dollar-denominated
Fair Value Measurement Inputs and Valuation Technique
Available for sale, fixed maturity securities		4,685	4,945
Public utilities | Yen-denominated
Fair Value Measurement Inputs and Valuation Technique
Available for sale, fixed maturity securities		5,366	5,872
Other corporate
Fair Value Measurement Inputs and Valuation Technique
Available for sale, fixed maturity securities		37,837	40,217
Other corporate | Level 3
Fair Value Measurement Inputs and Valuation Technique
Available for sale, fixed maturity securities		426	299
Other corporate | Discounted cash flow technique
Fair Value Measurement Inputs and Valuation Technique
Available for sale, fixed maturity securities		426	331
Other corporate | Discounted cash flow technique | Level 3
Fair Value Measurement Inputs and Valuation Technique
Available for sale, fixed maturity securities		426	299
Other corporate | Dollar-denominated
Fair Value Measurement Inputs and Valuation Technique
Available for sale, fixed maturity securities		29,180	30,393
Other corporate | Yen-denominated
Fair Value Measurement Inputs and Valuation Technique
Available for sale, fixed maturity securities		8,657	9,824
Sovereign and supranational
Fair Value Measurement Inputs and Valuation Technique
Available for sale, fixed maturity securities		1,115	1,382
Sovereign and supranational | Level 3
Fair Value Measurement Inputs and Valuation Technique
Available for sale, fixed maturity securities		43	48
Sovereign and supranational | Consensus pricing valuation technique
Fair Value Measurement Inputs and Valuation Technique
Available for sale, fixed maturity securities			48
Sovereign and supranational | Consensus pricing valuation technique | Level 3
Fair Value Measurement Inputs and Valuation Technique
Available for sale, fixed maturity securities			48
Sovereign and supranational | Discounted cash flow technique
Fair Value Measurement Inputs and Valuation Technique
Available for sale, fixed maturity securities		43
Sovereign and supranational | Discounted cash flow technique | Level 3
Fair Value Measurement Inputs and Valuation Technique
Available for sale, fixed maturity securities		43	48
Sovereign and supranational | Dollar-denominated
Fair Value Measurement Inputs and Valuation Technique
Available for sale, fixed maturity securities		273	293
Sovereign and supranational | Yen-denominated
Fair Value Measurement Inputs and Valuation Technique
Available for sale, fixed maturity securities		$ 842	$ 1,089

[1] Inputs derived from U.S. long-term rates to accommodate long maturity nature of the Company's swaps

[2] Inputs derived from Japan long-term rates to accommodate long maturity nature of the Company's swaps