Pension and Other Postretirement Benefits - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended	3 Months Ended	6 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Dec. 31, 2013	Dec. 31, 2014	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Settlements, curtailments and other	$ 1		$ 1
Third party contributions made to pension plans		37
Pension and Postretirement Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Company contributions made to various plans	17		28	5	9
Pension and Postretirement Plans [Member] | LMG Non-Qualified Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Company contributions made to various plans	8
Retiree Medical Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Reduction in Retirement benefit obligation due to changes made in defined benefit pension and retiree medical plans		$ 41