Pension and Other Benefit Plans - Narrative (Details) - USD ($) $ in Millions	3 Months Ended
	Jun. 30, 2017	Mar. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Employer contribution	$ 15
Deferred compensation plan, liability	$ 76	$ 67
Non-employee directors
Defined Benefit Plan Disclosure [Line Items]
Maximum deferral percentage	100.00%
Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Expected employer contributions during remainder of Fiscal 2018	$ 41