Consolidated Statement of Comprehensive Income (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Unrealized gains (losses) on marketable securities, deferred taxes	$ (1)	$ (19)	$ (110)
Deferred gains (losses) on cash flow hedges, deferred taxes	62	3	(14)
Realized (gains) losses on marketable securities, deferred taxes	1	59	177
Realized (gains) losses on cash flow hedges, deferred taxes	(38)	(27)	2
Employee benefit obligations, deferred taxes	(43)	82	(108)
Currency translation adjustments, deferred taxes	$ 34	$ 23	$ 12