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	12 Months Ended
	Jun. 30, 2014	Jun. 30, 2015
Defined Benefit Plan Disclosure [Line Items]
Increase in pension liability	$ 12	$ 12
Defined benefit plan contributions by third party	37
Harlequin's Defined Benefit Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Increase in pension liability		$ 15
Retiree Medical Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Reduction in post - retirement medical plan obligation due to changes made in retiree medical plans	$ 41