Stockholders' Equity Stockholders' Equity (Comprehensive Income) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 29, 2015	Mar. 30, 2014	Dec. 31, 2014	Dec. 31, 2013
Stockholders' Equity
Foreign exchange translation, Before tax amount	$ (69)	$ 6
Foreign exchange translation, Tax (expense) or benefit	0	0
Foreign exchange translation, Net of tax amount	(69)	6
Cash flow hedges and interest rate locks, Before tax amount	(7)	(1)
Cash flow hedges and interest rate locks, Tax (expense) or benefit	2	1
Cash flow hedges and interest rate locks, Net of tax amount	(5)	0
Unrealized gains (losses) on investments and other, net, Before tax amount	(6)	0
Unrealized gains (losses) on investments and other, net, Tax (expense) or benefit	0	0
Unrealized gains (losses) on investments and other, net Net of tax amount	(6)	0
Pension and other employee benefit plans, net, Before tax amount	285	224
Pension and other employee benefit plans, net, Tax (expense) or benefit	(100)	(79)
Pension and other employee benefit plans, net, Net of tax amount	185	145
Other comprehensive income (loss), before tax	203	229
Other Comprehensive Income (Loss), Tax (expense) or benefit	(98)	(78)
Other comprehensive income (loss), net of tax amount	105	151
Accumulated Other Comprehensive Income (Loss), Foreign exchange translation	(72)	53	(3)	47
Accumulated Other Comprehensive Income (Loss), Cash flow hedges and interest rate locks	(19)	(8)	(14)	(8)
Accumulated Other Comprehensive Income (Loss), Unrealized gains (losses) on investments, and other, net	(15)	(9)	(9)	(9)
Accumulated Other Comprehensive Income (Loss), Pension and other employee benefit plans, net	(7,247)	(4,998)	(7,432)	(5,143)
Accumulated Other Comprehensive Income (Loss), Net of Tax	$ (7,353)	$ (4,962)	$ (7,458)	$ (5,113)