Supplementary Data on Cash Flows (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Cash flows from operating activities:
Net income	$ 253	$ 108	$ 103	$ 109	$ 314	$ 267	$ 177	$ 290	$ 573	$ 1,048	$ 619
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation									23	21	17
Amortization of deferred policy acquisition costs									849	778	715
Deferred income tax expense									4	198	118
Realized gains and impairments on investments									(189)	(758)	(418)
Equity in earnings of limited partnerships									(113)	(161)	(131)
Net amortization of bond premium									49	36	28
Increase in deferred compensation									6	8	2
Limited partnership distributions									131	176	164
Increase in receivables, reinsurance recoverables and reserve credits									(159)	(112)	(166)
(Increase) decrease in prepaid expenses									(2)	24	63
Increase in deferred policy acquisition costs									(892)	(816)	(743)
Increase (decrease) in accounts payable and accrued expenses									98	18	(28)
Increase in accrued commissions and agent bonuses									35	28	20
Increase in loss reserves									106	148	99
Increase in future life policy benefits and claims reserves									24	34	31
Increase in unearned premiums									236	233	187
Net cash provided by operating activities									$ 779	$ 903	$ 577