Restructuring - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended		1 Months Ended	3 Months Ended		1 Months Ended	12 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Jul. 31, 2012 2012 Restructuring [Member] Employees	Sep. 30, 2012 2012 Restructuring [Member]	Dec. 31, 2012 2012 Restructuring [Member] Subsequent Event [Member]	Jul. 31, 2011 2011 Restructuring [Member] Employees	Dec. 31, 2011 2011 Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Number of areas pre restructuring					22
Number of areas post restructuring					17
No of Employees positions eliminated					700			700
Pre-tax restructuring charges	$ 44	$ 15	$ 51	$ 15		$ 44			$ 19
Pre-tax restructuring charges associated with this reorganization related to employee severance and benefit costs						39			18
Severance cost range start							20
Severance cost range end							30
Number of Employees positions eliminated open position								300
Employee severance and benefit cost payments through the balance sheet date			$ 29