Estimated Aggregate Pre-tax Amortization Expense Related to Intangible Assets (Detail) (USD $) In Millions, unless otherwise specified	Jun. 30, 2012
Expected Amortization Expense [Line Items]
Amortization expense remainder of 2012	$ 43
Amortization expense 2013	86
Amortization expense 2014	49
Amortization expense 2015	23
Amortization expense 2016	$ 21