Income Taxes - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2019	Mar. 31, 2018	Jun. 30, 2018
Income Tax Contingency [Line Items]
Income tax expense	$ 7	$ 3	$ 112	$ 292
Income (loss) before income tax (expense) benefit	$ 30	$ (1,107)	382	(797)
Provisional charges recorded			174
Gross income tax paid			107	116
Income tax refunds			$ 17	$ 6
U.S. Tax Cuts and Jobs Act [Member]
Income Tax Contingency [Line Items]
Income tax expense					$ 237
US Statutory Federal Tax Rate [Member]
Income Tax Contingency [Line Items]
U.S. statutory federal tax rate					21.00%