INVESTMENTS - Composition of Investments in Unrealized Loss Position (Detail)	Mar. 31, 2014	Dec. 31, 2013
Investments, Unrealized Loss Position [Line Items]
Percentage of Total Investments in an 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 an Unrealized Loss Position	94.00%	96.00%
Percentage of Total Unrealized Losses	87.00%	92.00%
Perpetual securities:
Investments, Unrealized Loss Position [Line Items]
Percentage of Total Investments in an Unrealized Loss Position	6.00%	4.00%
Percentage of Total Unrealized Losses	13.00%	8.00%
Japan government and agencies | Fixed Maturities
Investments, Unrealized Loss Position [Line Items]
Percentage of Total Investments in an Unrealized Loss Position	4.00%	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 an Unrealized Loss Position	14.00%	13.00%
Percentage of Total Unrealized Losses	12.00%	12.00%
Sovereign and Supranational | Fixed Maturities
Investments, Unrealized Loss Position [Line Items]
Percentage of Total Investments in an Unrealized Loss Position	4.00%	3.00%
Percentage of Total Unrealized Losses	3.00%	4.00%
Banks/financial Institutions | Fixed Maturities
Investments, Unrealized Loss Position [Line Items]
Percentage of Total Investments in an Unrealized Loss Position	19.00%	14.00%
Percentage of Total Unrealized Losses	26.00%	22.00%
Other Corporate | Fixed Maturities
Investments, Unrealized Loss Position [Line Items]
Percentage of Total Investments in an Unrealized Loss Position	53.00%	41.00%
Percentage of Total Unrealized Losses	46.00%	53.00%
Investment Grade | Perpetual securities:
Investments, Unrealized Loss Position [Line Items]
Percentage of unrealized losses attributable to securities that were investment grade	91.00%	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	100.00%	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	96.00%	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	62.00%	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	87.00%	91.00%