INVESTMENTS - Composition of Investments in Unrealized Loss Position (Details)	Dec. 31, 2014	Dec. 31, 2013
Investments, Unrealized Loss Position [Line Items]
Percentage Of Total Investments In Unrealized Loss Position	100.00%	100.00%
Percentage of Total Unrealized Losses	100.00%	100.00%
Fixed Maturities
Investments, Unrealized Loss Position [Line Items]
Percentage Of Total Investments In Unrealized Loss Position	95.00%	96.00%
Percentage of Total Unrealized Losses	89.00%	92.00%
Perpetual securities
Investments, Unrealized Loss Position [Line Items]
Percentage Of Total Investments In Unrealized Loss Position	5.00%	4.00%
Percentage of Total Unrealized Losses	11.00%	8.00%
Japan government and agencies | Fixed Maturities
Investments, Unrealized Loss Position [Line Items]
Percentage Of Total Investments In Unrealized Loss Position	0.00%	25.00%
Percentage of Total Unrealized Losses	0.00%	1.00%
Public utilities | Fixed Maturities
Investments, Unrealized Loss Position [Line Items]
Percentage Of Total Investments In Unrealized Loss Position	13.00%	13.00%
Percentage of Total Unrealized Losses	7.00%	12.00%
Sovereign and supranational | Fixed Maturities
Investments, Unrealized Loss Position [Line Items]
Percentage Of Total Investments In Unrealized Loss Position	3.00%	3.00%
Percentage of Total Unrealized Losses	2.00%	4.00%
Banks/financial Institutions | Fixed Maturities
Investments, Unrealized Loss Position [Line Items]
Percentage Of Total Investments In Unrealized Loss Position	14.00%	14.00%
Percentage of Total Unrealized Losses	33.00%	22.00%
Other corporate | Fixed Maturities
Investments, Unrealized Loss Position [Line Items]
Percentage Of Total Investments In Unrealized Loss Position	65.00%	41.00%
Percentage of Total Unrealized Losses	47.00%	53.00%
Investment Grade | Perpetual securities
Investments, Unrealized Loss Position [Line Items]
Percentage of unrealized losses attributable to securities that were investment grade	100.00%	90.00%
Investment Grade | Japan government and agencies | Fixed Maturities
Investments, Unrealized Loss Position [Line Items]
Percentage of unrealized losses attributable to securities that were investment grade	0.00%	100.00%
Investment Grade | Public utilities | Fixed Maturities
Investments, Unrealized Loss Position [Line Items]
Percentage of unrealized losses attributable to securities that were investment grade	100.00%	98.00%
Investment Grade | Sovereign and supranational | Fixed Maturities
Investments, Unrealized Loss Position [Line Items]
Percentage of unrealized losses attributable to securities that were investment grade	100.00%	100.00%
Investment Grade | Banks/financial Institutions | Fixed Maturities
Investments, Unrealized Loss Position [Line Items]
Percentage of unrealized losses attributable to securities that were investment grade	31.00%	64.00%
Investment Grade | Other corporate | Fixed Maturities
Investments, Unrealized Loss Position [Line Items]
Percentage of unrealized losses attributable to securities that were investment grade	88.00%	91.00%