Long-Term Debt - Additional Information (Detail) (USD $)	6 Months Ended
	Jun. 30, 2012
Debt Instrument [Line Items]
Aggregate principal amount	500,000,000
Debt instrument, interest rate	99.699%
Amount Available For Issuance Under Bank Note Program	4,700,000,000
Senior Subordinated Notes [Member]
Debt Instrument [Line Items]
Senior unsecured debt obligations with maturities	5 years
Bank note program [Member]
Debt Instrument [Line Items]
Senior Notes issued under bank note program	8,000,000,000
Senior bank notes 3.500% notes due 2022 [Member]
Debt Instrument [Line Items]
Aggregate principal amount	400,000,000
Debt instrument, interest rate	99.20%
Senior bank notes due on 2017 [Member]
Debt Instrument [Line Items]
Senior Notes bear interest	2.125%
2022 Senior Notes bear interest [Member]
Debt Instrument [Line Items]
Senior Notes bear interest	3.50%
Unsecured Debt [Member]
Debt Instrument [Line Items]
Senior unsecured debt obligations with maturities	1 year