Investments (Details 4) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Rollforward of the net unrealized securities gains (losses) on Available-for-Sale securities included in accumulated other comprehensive income
Net unrealized securities losses arising during the period	$ (141)	$ 42
Net realized gains and losses on Available-for-Sale securities
Gross realized investment gains		4
Other-than-temporary impairments	(1)	(1)
Total	(1)	3
Net Unrealized Securities Gains
Rollforward of the net unrealized securities gains (losses) on Available-for-Sale securities included in accumulated other comprehensive income
Balance at the beginning of the period	1,930	1,472
Net unrealized securities gains arising during the period		65
Net unrealized securities losses arising during the period	(217)
Reclassification of net securities (gains) losses included in net income	1	(3)
Impact on DAC, DSIC, benefit reserves and reinsurance recoverables	98	(5)
Balance at the end of the period	1,812	1,529
Deferred Income Tax
Rollforward of the net unrealized securities gains (losses) on Available-for-Sale securities included in accumulated other comprehensive income
Balance at the beginning of the period	(675)	(515)
Net unrealized securities gains arising during the period		(23)
Net unrealized securities losses arising during the period	76
Reclassification of net securities (gains) losses included in net income	(1)	1
Impact on DAC, DSIC, benefit reserves and reinsurance recoverables	(34)	2
Balance at the end of the period	(634)	(535)
Accumulated Other Comprehensive Income Related to Net Unrealized Securities Gains
Rollforward of the net unrealized securities gains (losses) on Available-for-Sale securities included in accumulated other comprehensive income
Balance at the beginning of the period	1,255	957
Net unrealized securities gains arising during the period		42
Net unrealized securities losses arising during the period	(141)
Reclassification of net securities (gains) losses included in net income		(2)
Impact on DAC, DSIC, benefit reserves and reinsurance recoverables	64	(3)
Balance at the end of the period	1,178	994
Noncredit related impairments on securities and net unrealized securities losses on previously impaired securities, included in Accumulated Other Comprehensive Income	$ (12)	$ (18)