Income Taxes - Additional Information Regarding Examinations (Detail) - USD ($) $ in Billions	3 Months Ended		6 Months Ended
	Sep. 30, 2015	Mar. 31, 2011	Dec. 31, 2015	Jun. 30, 2015
Income Tax Examination [Line Items]
Tax contingencies and other tax liabilities			$ 12.3	$ 12.1
Internal Revenue Service (IRS) | Earliest Tax Year
Income Tax Examination [Line Items]
Tax years under audit	2007	2004
Tax years subject to examination			2004
Internal Revenue Service (IRS) | Latest Tax Year
Income Tax Examination [Line Items]
Tax years under audit	2009	2006
Tax years subject to examination			2015
Foreign Country | Earliest Tax Year
Income Tax Examination [Line Items]
Tax years subject to examination			1996
Foreign Country | Latest Tax Year
Income Tax Examination [Line Items]
Tax years subject to examination			2015