v3.8.0.1
Equity (Accumulated Other Comprehensive Income (Loss) (Details) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]      
Beginning balance $ 14,621    
Income tax benefit (expense) (784) $ (1,305) $ 2,213
Ending balance 17,074 14,621  
Foreign Currency Translation Adjustment      
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]      
Beginning balance (973) (1,087) (975)
Change in OCI before reclassifications 768 199 (245)
Amounts reclassified from AOCI 1 13 17
Income tax benefit (expense) (65) (98) 116
Ending balance (269) (973) (1,087)
Net Unrealized Investment Gains (Losses)      
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]      
Beginning balance 18,171 15,773 19,251
Change in OCI before reclassifications 4,026 5,176 (3,161)
Amounts reclassified from AOCI (1,629) (1,493) (2,325)
Income tax benefit (expense) (600) (1,285) 2,008
Ending balance 19,968 18,171 15,773
Pension and Postretirement Unrecognized Net Periodic Benefit (Cost)      
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]      
Beginning balance (2,577) (2,401) (2,226)
Change in OCI before reclassifications (153) (468) (457)
Amounts reclassified from AOCI 224 214 193
Income tax benefit (expense) (119) 78 89
Ending balance (2,625) (2,577) (2,401)
Accumulated Other Comprehensive Income (Loss)      
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]      
Beginning balance 14,621 12,285 16,050
Change in OCI before reclassifications 4,641 4,907 (3,863)
Amounts reclassified from AOCI (1,404) (1,266) (2,115)
Income tax benefit (expense) (784) (1,305) 2,213
Ending balance 17,074 14,621 12,285
Cash flow hedges | Net Unrealized Investment Gains (Losses)      
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]      
Beginning balance 1,316 1,165  
Ending balance $ (39) $ 1,316 $ 1,165