Line items represent reporting concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Investments (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended		6 Months Ended
Investments (Details) - USD ($) $ in Millions	Jan. 27, 2018	Jun. 30, 2018	Jul. 01, 2017	Jun. 30, 2018	Jul. 01, 2017	Dec. 31, 2017
Investments
Fair Value		$ 1,264		$ 1,264		$ 1,576
Total trading short-term investments		1,264		1,264		1,576
Change in unrealized gains (losses) on trading securities		(2)	$ 33	(24)	$ 65
Domestic equity securities
Investments
Fair Value Equity		772		772		752
Foreign equity securities
Investments
Fair Value Equity		302		302		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		23		23		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		15		15		15
Domestic debt securities held in mutual funds/ETFs/U.S. Treasuries
Investments
Fair Value		122		122		439
Proceeds from sale of securities	$ 314
Collateralized loan obligation
Investments
Fair Value		30		30		29
High yield securities
Investments
Fair Value		21		21		21
Money market funds held in trading accounts
Investments
Fair Value		10		10		10
Money market funds held in trading accounts \| Denominated in foreign currencies \| Maximum
Investments
Fair Value		1		1		1
Other trading securities
Investments
Fair Value		$ 7		$ 7		$ 6