Pension and Other Postretirement Benefits - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended	3 Months Ended				9 Months Ended
	Mar. 31, 2014	Sep. 30, 2013	Mar. 31, 2014	Sep. 30, 2013 Retiree Medical Plans [Member]	Mar. 31, 2014 Domestic Pension Benefits Plans [Member]	Mar. 31, 2014 Pension and Postretirement Plans [Member]	Mar. 31, 2013 Pension and Postretirement Plans [Member]	Mar. 31, 2014 Pension and Postretirement Plans [Member]	Mar. 31, 2013 Pension and Postretirement Plans [Member]	Mar. 31, 2014 Pension and Postretirement Plans [Member] LMG Non-Qualified Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Settlements, curtailments and other	$ 0		$ 1
Company contributions made to various plans						13	37	41	63	8
Third party contributions made to pension plans		37
Reduction in retirement benefit obligation due to changes made in defined benefit pension and retiree medical plans			$ 69	$ 41	$ 28