Annual report pursuant to Section 13 and 15(d)

CASH AND INVESTMENTS - Changes in Level 3 Instruments Measured on a Recurring Basis (Detail)

v3.8.0.1
CASH AND INVESTMENTS - Changes in Level 3 Instruments Measured on a Recurring Basis (Detail) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]    
Beginning Balance $ 13 $ 32
Transfers into (out of) Level 3 0 0
Net realized and unrealized gains (losses):    
Included in earnings (in investment income) (7) (19)
Included in accumulated other comprehensive income (pre-tax) 0 0
Purchases 0 0
Settlements 0 0
Ending Balance 6 13
Marketable securities    
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]    
Beginning Balance 0 0
Transfers into (out of) Level 3 0 0
Net realized and unrealized gains (losses):    
Included in earnings (in investment income) 0 0
Included in accumulated other comprehensive income (pre-tax) 0 0
Purchases 0 0
Settlements 0 0
Ending Balance 0 0
Other Long-term Investments    
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]    
Beginning Balance 13 32
Transfers into (out of) Level 3 0 0
Net realized and unrealized gains (losses):    
Included in earnings (in investment income) (7) (19)
Included in accumulated other comprehensive income (pre-tax) 0 0
Purchases 0 0
Settlements 0 0
Ending Balance $ 6 $ 13