Employee Pension and Other Benefit Plans - Plan Amendment and Other Remeasurements (Details) - Other Benefit Plans - Post-Retirement Medical and Life Insurance Plan $ in Millions	3 Months Ended
	Jun. 30, 2014 USD ($)
Re-measurement assumptions and related information
Discount rate (as a percent)	4.74%
Increase (decrease) in pension or post-retirement benefit plan liability, before tax	$ (52)
Increase (decrease) in pension or post-retirement benefit plan liability, net of tax	$ (34)