v3.7.0.1
Fair Value Disclosures - Changes in Level 3 Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($)
$ in Millions
3 Months Ended 6 Months Ended
Jun. 30, 2017
Jun. 30, 2016
Jun. 30, 2017
Jun. 30, 2016
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]        
Assets measured at fair value, beginning balance $ 113 $ 219 $ 143 $ 221
Realized and Unrealized Gains (Losses) in Earnings and OCI, Assets     1 2
Purchases, Assets 27   27 27
Sales and Maturities, Assets   (3)   (9)
Transfers out of Level 3, Assets   (24) (31) (49)
Assets measured at fair value, ending balance 140 192 140 192
Available-for-sale Securities [Member]        
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]        
Assets measured at fair value, beginning balance   23 24 23
Purchases, Assets 23   23 23
Transfers out of Level 3, Assets   (23) (24) (46)
Assets measured at fair value, ending balance 23   23  
Consolidated Variable Interest Entities [Member] | Other Liabilities [Member]        
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]        
Liabilities measured at fair value, beginning balance 113 49 115 48
Realized and Unrealized Gains (Losses) in Earnings and OCI, Liabilities 3 3 5 2
Issuances and other Settlements, Liabilities 108 75 108 75
Liabilities measured at fair value, ending balance 218 121 218 121
Total Net Unrealized Gains (Losses) Included in Earnings 3 3 5 2
Consolidated Variable Interest Entities [Member] | Private/ Public Equity [Member]        
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]        
Assets measured at fair value, beginning balance 113 192 112 196
Realized and Unrealized Gains (Losses) in Earnings and OCI, Assets     1 2
Sales and Maturities, Assets   (3)   (9)
Assets measured at fair value, ending balance 113 189 113 189
Total Net Unrealized Gains (Losses) Included in Earnings     1 2
Trading [Member]        
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]        
Assets measured at fair value, beginning balance   4 7 2
Purchases, Assets 4   4 4
Transfers out of Level 3, Assets   (1) (7) (3)
Assets measured at fair value, ending balance 4 3 4 3
Investments [Member]        
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]        
Assets measured at fair value, beginning balance   27 31 25
Purchases, Assets 27   27 27
Transfers out of Level 3, Assets   (24) (31) (49)
Assets measured at fair value, ending balance $ 27 $ 3 $ 27 $ 3