Consolidated Statements of Comprehensive Income Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Comprehensive Income
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	$ 421	$ 381	$ 413	$ 467	$ 382	$ 388	$ (467)	$ 495	$ 1,682	$ 798	$ 176
Comprehensive Income (Loss), Net of Tax, Attributable to Parent									425	1,805	(2,746)
Other comprehensive income
Other Comprehensive Income (Loss), Net of Tax									(1,257)	1,007	(2,922)
Accumulated Net Unrealized Investment Gain (Loss) [Member]
Other comprehensive income
Other Comprehensive Income (Loss), Net of Tax									(1,091)	1,383	(2,431)
Accumulated Other-than-Temporary Impairment [Member]
Other comprehensive income
Other Comprehensive Income (Loss), Net of Tax									(2)	7	35
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]
Other comprehensive income
Other Comprehensive Income (Loss), Net of Tax									(20)	42	(320)
Accumulated Translation Adjustment [Member]
Other comprehensive income
Other Comprehensive Income (Loss), Net of Tax									(47)	(99)	(315)
Accumulated Defined Benefit Plans Adjustment [Member]
Other comprehensive income
Other Comprehensive Income (Loss), Net of Tax									$ (97)	$ (326)	$ 109