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Investments (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
Investments (Details) - USD ($) $ in Millions	Sep. 29, 2018	Sep. 30, 2017	Sep. 29, 2018	Sep. 30, 2017	Dec. 31, 2017
Investments
Fair Value	$ 1,590		$ 1,590		$ 1,576
Total trading short-term investments	1,590		1,590		1,576
Change in unrealized gains (losses) on trading securities	37	$ 54	15	$ 114
Domestic equity securities
Investments
Fair Value Equity	812		812		752
Domestic debt securities held in mutual funds/ETFs/U.S. Treasuries
Investments
Fair Value	399		399		439
Foreign equity securities
Investments
Fair Value Equity	305		305		319
Foreign equity securities \| Denominated in foreign currencies
Investments
Fair Value Equity	107		107		114
Foreign equity securities \| Denominated in Euros
Investments
Fair Value Equity	43		43		48
Foreign equity securities \| Denominated in Japanese Yen
Investments
Fair Value Equity	24		24		25
Foreign equity securities \| Denominated in British pounds
Investments
Fair Value Equity	20		20		20
Foreign equity securities \| Denominated in Swiss Franc
Investments
Fair Value Equity	6		6		6
Foreign equity securities \| Denominated in other foreign currencies
Investments
Fair Value Equity	14		14		15
Collateralized loan obligation
Investments
Fair Value	31		31		29
High yield securities
Investments
Fair Value	21		21		21
Term deposits
Investments
Fair Value	10		10
Money market funds held in trading accounts
Investments
Fair Value	7		7		10
Other trading securities
Investments
Fair Value	$ 5		$ 5		$ 6