Derivatives (Details) In Billions, unless otherwise specified	Sep. 30, 2014 USD ($)	Sep. 30, 2014 JPY (¥)	Dec. 31, 2013 USD ($)	Dec. 31, 2013 JPY (¥)	Mar. 01, 2007 USD ($)	Mar. 01, 2007 JPY (¥)	Sep. 01, 2006 USD ($)	Sep. 01, 2006 JPY (¥)
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Notional amount	$ 1.4	¥ 156.8	$ 1.9	¥ 203.6	$ 0.5	¥ 56.0	$ 1.7	¥ 200.0
Collective account values of underlying variable annuities as a percentage of the guarantee value	107.00%	107.00%	104.00%	104.00%