Intangible Assets and Goodwill (Amortized Intangible Assets, Excluding Goodwill, By Business Segment) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 1,251	$ 1,162
Accumulated Amortization	1,142	1,114
Government
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	53	53
Accumulated Amortization	48	48
Enterprise
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	1,198	1,109
Accumulated Amortization	$ 1,094	$ 1,066