Income Taxes - Additional Information Regarding Examinations (Detail) - USD ($) $ in Billions	3 Months Ended	6 Months Ended	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2020	Jun. 30, 2018	Jun. 30, 2016	Jun. 30, 2011
Earliest Tax Year | Foreign Country
Income Tax Examination [Line Items]
Tax years subject to examination		1996
Latest Tax Year | Foreign Country
Income Tax Examination [Line Items]
Tax years subject to examination		2020
Internal Revenue Service (IRS)
Income Tax Examination [Line Items]
Settlement payments including tax and interest	$ 1.7
Internal Revenue Service (IRS) | Earliest Tax Year
Income Tax Examination [Line Items]
Tax years under audit	2004		2010	2007	2004
Tax years subject to examination		2004
Internal Revenue Service (IRS) | Latest Tax Year
Income Tax Examination [Line Items]
Tax years under audit	2013		2013	2009	2006
Tax years subject to examination		2017