Retirement Benefit Obligations - Schedule of Change in Projected Benefit Obligation, Change in Fair Value of Plan Assets and Funded Status (Parenthetical) (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended	12 Months Ended
	Sep. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Compensation And Retirement Disclosure [Abstract]
Defined benefit plan contributions by third party	$ 37
Defined benefit plan contributions related to Separation			115
Assets received upon Separation	$ 20	$ 58