Postretirement Benefits (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended		12 Months Ended
	Mar. 31, 2014 Pension Benefits	Mar. 31, 2013 Pension Benefits	Mar. 31, 2014 Pension Benefits	Mar. 31, 2013 Pension Benefits	Mar. 31, 2014 Other Retiree Benefits	Mar. 31, 2013 Other Retiree Benefits	Mar. 31, 2014 Other Retiree Benefits	Mar. 31, 2013 Other Retiree Benefits	Jun. 30, 2014 Forecast [Member] Pension Benefits	Jun. 30, 2014 Forecast [Member] Other Retiree Benefits
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service Cost	$ 76	$ 76	$ 223	$ 226	$ 37	$ 48	$ 112	$ 143
Interest Cost	149	140	440	421	64	65	192	195
Expected Return on Plan Assets	(177)	(146)	(523)	(442)	(96)	(95)	(289)	(286)
Amortization of Deferred Amounts	6	4	19	13	(5)	(5)	(15)	(15)
Recognized Net Actuarial Loss	54	55	160	161	29	49	88	149
Curtailment loss			0	(2)			0	0
Settlement loss	0	2	0	2	0	0	0	0
Gross Benefit Cost (Credit)	108	131	319	383	29	62	88	186
Dividends on ESOP Preferred Stock	0	0	0	0	(16)	(17)	(48)	(52)
Net Periodic Benefit Cost (Credit)	$ 108	$ 131	$ 319	$ 383	$ 13	$ 45	$ 40	$ 134
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract]
Expected Long-term Return on Assets									7.20%	8.30%