Other Financial Data (Sigma Fund) (Details) (USD $) In Millions, unless otherwise specified	Sep. 28, 2013	Dec. 31, 2012
Sigma Fund
Sigma Fund	$ 1,167	$ 2,133
Cash [Mmeber]
Sigma Fund
Sigma Fund	261	149
U.S. Government, Agency and Government-sponsored Enterprise Obligations [Member]
Sigma Fund
Sigma Fund	$ 906	$ 1,984