FAIR VALUE MEASUREMENTS Fair Value Inputs Assets Quantitative Information (Details) - USD ($) $ / shares in Units, $ in Millions		3 Months Ended	12 Months Ended
		Mar. 31, 2016	Dec. 31, 2015
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Available-for-sale Securities		$ 74,906	$ 67,794
Asset derivatives		1,144	676
Assets, fair value		$ 79,697	$ 72,996
Length of Volatility of Japanese Yen to US Dollar Exchange Rate		10 years	10 years
Level 3
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Available-for-sale Securities		$ 266	$ 249
Asset derivatives		114	102
Assets, fair value		380	351
Fixed maturities
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Available-for-sale Securities		72,128	65,349
Fixed maturities | Level 3
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Available-for-sale Securities		263	246
Perpetual securities
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Available-for-sale Securities		1,909	1,947
Perpetual securities | Level 3
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Available-for-sale Securities		0	0
Equity securities
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Available-for-sale Securities		869	498
Equity securities | Level 3
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Available-for-sale Securities		3	3
Equity securities | Net asset value valuation technique
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Available-for-sale Securities		3	3
Equity securities | Net asset value valuation technique | Level 3
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Available-for-sale Securities		$ 3	$ 3
Equity securities | Assets | Lower Limit | Level 3
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Inputs, Offered Quotes		$ 1	$ 1
Equity securities | Assets | Upper Limit | Level 3
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Inputs, Offered Quotes		724	677
Equity securities | Assets | Weighted Average | Level 3
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Inputs, Offered Quotes		$ 8	$ 7
Mortgage- and asset-backed securities | Fixed maturities
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Available-for-sale Securities		$ 605	$ 582
Mortgage- and asset-backed securities | Fixed maturities | Level 3
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Available-for-sale Securities		237	220
Mortgage- and asset-backed securities | Fixed maturities | Consensus pricing valuation technique
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Available-for-sale Securities		237	220
Mortgage- and asset-backed securities | Fixed maturities | Consensus pricing valuation technique | Level 3
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Available-for-sale Securities		237	220
Banks/financial institutions | Fixed maturities
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Available-for-sale Securities		5,856	6,019
Banks/financial institutions | Fixed maturities | Level 3
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Available-for-sale Securities		26	26
Banks/financial institutions | Fixed maturities | Consensus pricing valuation technique
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Available-for-sale Securities		26	26
Banks/financial institutions | Fixed maturities | Consensus pricing valuation technique | Level 3
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Available-for-sale Securities		26	26
Banks/financial institutions | Perpetual securities
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Available-for-sale Securities		1,692	1,742
Banks/financial institutions | Perpetual securities | Level 3
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Available-for-sale Securities		0	0
Banks/financial institutions | Perpetual securities | Consensus pricing valuation technique
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Available-for-sale Securities		44
Banks/financial institutions | Perpetual securities | Consensus pricing valuation technique | Level 3
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Available-for-sale Securities		0
Foreign currency swaps
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Asset derivatives		493	563
Foreign currency swaps | Level 3
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Asset derivatives		112	101
Credit default swaps
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Asset derivatives		2	1
Credit default swaps | Level 3
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Asset derivatives		2	1
Fair Value, Unobservable Input, Interest Rates (USD), Interest Rates (JPY), CDS Spreads and Foreign Exchange Rates | Foreign currency swaps | Discounted cash flow valuation technique | Level 3
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Asset derivatives		$ 15	$ 7
Fair Value, Unobservable Input, Interest Rates (USD), Interest Rates (JPY), CDS Spreads and Foreign Exchange Rates | Foreign currency swaps | Assets | Level 3
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Inputs, Foreign Exchange Rates	[1]	20.34%	20.05%
Fair Value, Unobservable Input, Interest Rates (USD), Interest Rates (JPY), CDS Spreads and Foreign Exchange Rates | Foreign currency swaps | Assets | Lower Limit | Level 3
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Inputs, Entity Credit Risk		0.32%	0.32%
Fair Value, Unobservable Input, Interest Rates (USD), Interest Rates (JPY), CDS Spreads and Foreign Exchange Rates | Foreign currency swaps | Assets | Upper Limit | Level 3
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Inputs, Entity Credit Risk		1.47%	1.47%
Fair Value, Unobservable Input, Interest Rates (USD), Interest Rates (JPY), and CDS Spread | Foreign currency swaps | Discounted cash flow valuation technique | Level 3
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Asset derivatives		$ 12
Fair Value, Unobservable Input, Interest Rates (USD), Interest Rates (JPY), and CDS Spread | Foreign currency swaps | Assets | Lower Limit | Level 3
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Inputs, Entity Credit Risk		0.12%
Fair Value, Unobservable Input, Interest Rates (USD), Interest Rates (JPY), and CDS Spread | Foreign currency swaps | Assets | Upper Limit | Level 3
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Inputs, Entity Credit Risk		0.82%
Fair Value, Unobservable Input, Interest Rates (USD), Interest Rates (JPY), and Foreign Exchange Rates | Foreign currency swaps | Discounted cash flow valuation technique | Level 3
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Asset derivatives		$ 85	$ 94
Fair Value, Unobservable Input, Interest Rates (USD), Interest Rates (JPY), and Foreign Exchange Rates | Foreign currency swaps | Assets | Level 3
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Inputs, Foreign Exchange Rates	[1]	20.34%	20.05%
Fair Value, Unobservable Input, Base Correlation, CDS Spreads, Recovery Rate | Credit default swaps | Discounted cash flow valuation technique | Level 3
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Asset derivatives		$ 2	$ 1
Fair Value, Unobservable Input, Base Correlation, CDS Spreads, Recovery Rate | Credit default swaps | Assets | Level 3
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Inputs, Entity Credit Risk		0.84%	1.23%
Fair Value Inputs, Recovery Rate		36.95%	36.87%
Fair Value, Unobservable Input, Base Correlation, CDS Spreads, Recovery Rate | Credit default swaps | Assets | Lower Limit | Level 3
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Inputs, Base Correlation	[2]	64.18%	53.26%
Fair Value, Unobservable Input, Base Correlation, CDS Spreads, Recovery Rate | Credit default swaps | Assets | Upper Limit | Level 3
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Inputs, Base Correlation	[2]	69.87%	58.40%
Dollar-denominated | Fixed maturities
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Available-for-sale Securities		$ 38,483	$ 36,838
Dollar-denominated | Equity securities
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Available-for-sale Securities		289	11
Dollar-denominated | Mortgage- and asset-backed securities | Fixed maturities
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Available-for-sale Securities		229	227
Dollar-denominated | Banks/financial institutions | Fixed maturities
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Available-for-sale Securities		3,172	3,478
Dollar-denominated | Banks/financial institutions | Perpetual securities
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Available-for-sale Securities		$ 72	$ 111
Dollar-denominated | Fair Value, Unobservable Input, Interest Rates (USD), Interest Rates (JPY), CDS Spreads and Foreign Exchange Rates | Foreign currency swaps | Assets | Lower Limit | Level 3
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Inputs, Discount Rate	[3]	1.64%	2.20%
Dollar-denominated | Fair Value, Unobservable Input, Interest Rates (USD), Interest Rates (JPY), CDS Spreads and Foreign Exchange Rates | Foreign currency swaps | Assets | Upper Limit | Level 3
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Inputs, Discount Rate	[3]	2.14%	2.62%
Dollar-denominated | Fair Value, Unobservable Input, Interest Rates (USD), Interest Rates (JPY), and CDS Spread | Foreign currency swaps | Assets | Lower Limit | Level 3
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Inputs, Discount Rate	[3]	1.64%
Dollar-denominated | Fair Value, Unobservable Input, Interest Rates (USD), Interest Rates (JPY), and CDS Spread | Foreign currency swaps | Assets | Upper Limit | Level 3
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Inputs, Discount Rate	[3]	2.14%
Dollar-denominated | Fair Value, Unobservable Input, Interest Rates (USD), Interest Rates (JPY), and Foreign Exchange Rates | Foreign currency swaps | Assets | Lower Limit | Level 3
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Inputs, Discount Rate	[3]	1.64%	2.20%
Dollar-denominated | Fair Value, Unobservable Input, Interest Rates (USD), Interest Rates (JPY), and Foreign Exchange Rates | Foreign currency swaps | Assets | Upper Limit | Level 3
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Inputs, Discount Rate	[3]	2.14%	2.62%
Yen-denominated | Fixed maturities
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Available-for-sale Securities		$ 33,645	$ 28,511
Yen-denominated | Equity securities
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Available-for-sale Securities		580	487
Yen-denominated | Mortgage- and asset-backed securities | Fixed maturities
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Available-for-sale Securities		376	355
Yen-denominated | Banks/financial institutions | Fixed maturities
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Available-for-sale Securities		2,684	2,541
Yen-denominated | Banks/financial institutions | Perpetual securities
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Available-for-sale Securities		$ 1,620	$ 1,631
Yen-denominated | Fair Value, Unobservable Input, Interest Rates (USD), Interest Rates (JPY), CDS Spreads and Foreign Exchange Rates | Foreign currency swaps | Assets | Lower Limit | Level 3
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Inputs, Discount Rate	[4]	0.15%	0.42%
Yen-denominated | Fair Value, Unobservable Input, Interest Rates (USD), Interest Rates (JPY), CDS Spreads and Foreign Exchange Rates | Foreign currency swaps | Assets | Upper Limit | Level 3
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Inputs, Discount Rate	[4]	0.60%	1.22%
Yen-denominated | Fair Value, Unobservable Input, Interest Rates (USD), Interest Rates (JPY), and CDS Spread | Foreign currency swaps | Assets | Lower Limit | Level 3
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Inputs, Discount Rate	[4]	0.15%
Yen-denominated | Fair Value, Unobservable Input, Interest Rates (USD), Interest Rates (JPY), and CDS Spread | Foreign currency swaps | Assets | Upper Limit | Level 3
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Inputs, Discount Rate	[4]	0.60%
Yen-denominated | Fair Value, Unobservable Input, Interest Rates (USD), Interest Rates (JPY), and Foreign Exchange Rates | Foreign currency swaps | Assets | Lower Limit | Level 3
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Inputs, Discount Rate	[4]	0.15%	0.42%
Yen-denominated | Fair Value, Unobservable Input, Interest Rates (USD), Interest Rates (JPY), and Foreign Exchange Rates | Foreign currency swaps | Assets | Upper Limit | Level 3
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Inputs, Discount Rate	[4]	0.60%	1.22%

[1] Based on 10 year volatility of JPY/USD exchange rate

[2] Range of base correlation for our bespoke tranche for attachment and detachment points corresponding to market indices.

[3] Inputs derived from U.S. long-term rates to accommodate long maturity nature of our swaps

[4] Inputs derived from Japan long-term rates to accommodate long maturity nature of our swaps