Annual report pursuant to Section 13 and 15(d)

Fair Value Measurements - Schedule of Reconciliation of Level 3 Investments Available-for-Sale Securities (Detail)

v3.3.1.900
Fair Value Measurements - Schedule of Reconciliation of Level 3 Investments Available-for-Sale Securities (Detail) - Investments Available-for-Sale [Member] - Debt Securities [Member] - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2015
Dec. 31, 2014
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]    
Balance, beginning of period $ 27  
Transfers to / purchases of available-for-sale debt securities. 33 $ 83
Payments on available-for-sale debt securities (8)  
Sale of available-for-sale debt securities (22) (60)
Unrealized gains on debt securities transferred to available for sale   5
Gains on debt securities recorded in earnings 1 3
Losses on debt securities recorded in OCI (2) (4)
Balance, end of Period $ 29 $ 27