Acquisitions, Divestitures, Goodwill and Intangible Assets - Amortization Life (Detail)	12 Months Ended
	Dec. 31, 2012
Contract and Program Intangible Assets | Minimum
Finite-Lived Intangible Assets [Line Items]
Range of Amortization Life	7 years
Contract and Program Intangible Assets | Maximum
Finite-Lived Intangible Assets [Line Items]
Range of Amortization Life	30 years
Tradenames and Trademarks
Finite-Lived Intangible Assets [Line Items]
Range of Amortization Life	30 years
Technology and Software | Minimum
Finite-Lived Intangible Assets [Line Items]
Range of Amortization Life	7 years
Technology and Software | Maximum
Finite-Lived Intangible Assets [Line Items]
Range of Amortization Life	15 years
Other Intangible Assets | Minimum
Finite-Lived Intangible Assets [Line Items]
Range of Amortization Life	3 years
Other Intangible Assets | Maximum
Finite-Lived Intangible Assets [Line Items]
Range of Amortization Life	7 years