v3.10.0.1
Accumulated Other Comprehensive Income - Changes in Accumulated Balances of Other Comprehensive Income (Details) - USD ($)
$ in Millions
3 Months Ended 9 Months Ended
Sep. 30, 2018
Sep. 30, 2017
Sep. 30, 2018
Sep. 30, 2017
Accumulated Other Comprehensive Income (Loss), Tax        
Accumulated other comprehensive income (loss), estimated tax (expense) benefit, beginning balance $ 28 $ 33 $ 41 $ 1
Other comprehensive income (loss) before reclassifications, tax (1) 3 (3) 35
Less: Amount of gain (loss) reclassified from accumulated other comprehensive income, tax (3) 0 8 0
Net current period other comprehensive income, tax 2 3 (11) 35
Accumulated other comprehensive income (loss), estimated tax (expense) benefit, ending balance 30 36 30 36
Accumulated Other Comprehensive Income (Loss), Net of Tax        
Beginning balance     8,049  
Less: Amount of gain (loss) reclassified from accumulated other comprehensive income 9 (11) (30) 41
Other comprehensive income/(loss), net of tax (31) 101 (167) 662
Ending balance 6,929   6,929  
Unrealized Gains (Losses) on Cash Flow Hedges        
Accumulated Other Comprehensive Income (Loss), Before Tax        
Accumulated other comprehensive income (loss), before tax, beginning balance 51 (44) (57) 54
Other comprehensive income (loss), before reclassifications, before tax (4) (31) 55 (94)
Less: Amount of gain (loss) reclassified from accumulated other comprehensive income, before tax 12 (7) (37) 28
Net current period other comprehensive income, before tax (16) (24) 92 (122)
Accumulated other comprehensive income (loss), before tax, ending balance 35 (68) 35 (68)
Unrealized Gains on Investments        
Accumulated Other Comprehensive Income (Loss), Before Tax        
Accumulated other comprehensive income (loss), before tax, beginning balance (53) 2 (15) 51
Other comprehensive income (loss), before reclassifications, before tax 8 3 (31) (29)
Less: Amount of gain (loss) reclassified from accumulated other comprehensive income, before tax 0 (4) (1) 13
Net current period other comprehensive income, before tax 8 7 (30) (42)
Accumulated other comprehensive income (loss), before tax, ending balance (45) 9 (45) 9
Foreign Currency Translation        
Accumulated Other Comprehensive Income (Loss), Before Tax        
Accumulated other comprehensive income (loss), before tax, beginning balance 555 446 748 (230)
Other comprehensive income (loss), before reclassifications, before tax (25) 115 (218) 791
Less: Amount of gain (loss) reclassified from accumulated other comprehensive income, before tax 0 0 0 0
Net current period other comprehensive income, before tax (25) 115 (218) 791
Accumulated other comprehensive income (loss), before tax, ending balance 530 561 530 561
Total        
Accumulated Other Comprehensive Income (Loss), Net of Tax        
Beginning balance 581 437 717 (124)
Other comprehensive income (loss) before reclassifications (22) 90 (197) 703
Less: Amount of gain (loss) reclassified from accumulated other comprehensive income 9 (11) (30) 41
Other comprehensive income/(loss), net of tax (31) 101 (167) 662
Ending balance $ 550 $ 538 $ 550 $ 538