Liabilities for Unpaid Claims and Claims Expenses - Long-term Disability Claims Development Tables (Details) - Long-term Disability [Member] $ in Millions	12 Months Ended
	Dec. 31, 2016 USD ($) Claims	Dec. 31, 2015 USD ($) Claims	Dec. 31, 2014 USD ($) Claims	Dec. 31, 2013 USD ($) Claims	Dec. 31, 2012 USD ($) Claims
Claims Development [Line Items]
Incurred claims	$ 5,522
Cumulative Paid Claims	2,285
All outstanding liabilities prior to 2012, net of reinsurance	1,361
Impact of discounting	(976)
Liability for unpaid claims and claims expenses, net of reinsurance	$ 3,622
Claims frequency, methodology	The claims frequency metric used for the Company’s long-term disability line of business represents the number of unique claim events for which benefits have been approved and payments made. Claim events are identified using a unique claimant identifier and incurral date. Thus, if an individual has multiple claims for different disabling events (and therefore different incurral dates), each will be determined to be a unique claim event. However, if an individual receives multiple benefits under more than one policy (for example for supplemental disability benefits such as pension contribution benefits or survivor benefits), the Company treats this as a single claim occurrence because they related to the same claim event. Claims frequency metrics for the most recent year are expected to be low reflecting the long-term disability product features including waiting and elimination periods that result in delayed eligibility for contract benefits.
Accident Year 2012 [Member]
Claims Development [Line Items]
Incurred claims	$ 883	$ 876	$ 889	$ 951	$ 995
Cumulative Paid Claims	571	504	429	288	$ 81
Incurred But Not Reported Liabilities	0
Claim frequency | Claims					21,170
Accident Year 2013 [Member]
Claims Development [Line Items]
Incurred claims	1,072	1,062	1,037	1,063
Cumulative Paid Claims	600	503	342	$ 92
Incurred But Not Reported Liabilities	0
Claim frequency | Claims				23,493
Accident Year 2014 [Member]
Claims Development [Line Items]
Incurred claims	1,167	1,129	1,158
Cumulative Paid Claims	575	379	$ 111
Incurred But Not Reported Liabilities	3
Claim frequency | Claims			25,175
Accident Year 2015 [Member]
Claims Development [Line Items]
Incurred claims	1,154	1,184
Cumulative Paid Claims	417	$ 114
Incurred But Not Reported Liabilities	17
Claim frequency | Claims		25,133
Accident Year 2016 [Member]
Claims Development [Line Items]
Incurred claims	1,246
Cumulative Paid Claims	122
Incurred But Not Reported Liabilities	$ 524
Claim frequency | Claims	13,734