Consolidated Statements of Comprehensive Income Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Comprehensive Income
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	$ (81)	$ 438	$ 216	$ 323	$ 421	$ 381	$ 413	$ 467	$ 896	$ 1,682	$ 798
Comprehensive Income (Loss), Net of Tax, Attributable to Parent									888	425	1,805
Other comprehensive income
Other Comprehensive Income (Loss), Net of Tax									(8)	(1,257)	1,007
Accumulated Net Unrealized Investment Gain (Loss) [Member]
Other comprehensive income
Other Comprehensive Income (Loss), Net of Tax									(3)	(1,091)	1,383
Accumulated Other-than-Temporary Impairment [Member]
Other comprehensive income
Other Comprehensive Income (Loss), Net of Tax									4	(2)	7
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]
Other comprehensive income
Other Comprehensive Income (Loss), Net of Tax									(54)	(20)	42
Accumulated Translation Adjustment [Member]
Other comprehensive income
Other Comprehensive Income (Loss), Net of Tax									61	(47)	(99)
Accumulated Defined Benefit Plans Adjustment [Member]
Other comprehensive income
Other Comprehensive Income (Loss), Net of Tax									$ (16)	$ (97)	$ (326)