Income Taxes - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		12 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013
Income Tax Disclosure [Abstract]
Tax Litigation			$ 593
Tax reserves	869		866
Impact on tax expense if tax reserves were unnecessary	869
Accrued interest, related to income taxes in the balance sheet	204
Additional tax expense related to interest	1	289
Reasonably possible decrease in uncertain tax positions within the next 12 months, if a re-evaluation is required	$ 270