Restructuring - Narrative (Details) - Cost Alignment Plan - USD ($) $ in Millions	3 Months Ended		9 Months Ended	10 Months Ended
	Dec. 31, 2016	Mar. 31, 2016	Dec. 31, 2016	Dec. 31, 2016
Restructuring Cost and Reserve [Line Items]
Pre-tax charges recorded during period	$ 5	$ 229	$ 4
Restructuring liabilities	112	$ 222	112	$ 112
Pre-tax restructuring charges incurred to-date				233
Minimum
Restructuring Cost and Reserve [Line Items]
Expected total pre-tax charges	250		250	250
Maximum
Restructuring Cost and Reserve [Line Items]
Expected total pre-tax charges	270		270	270
Other Accrued Liabilities
Restructuring Cost and Reserve [Line Items]
Restructuring liabilities	71		71	71
Other Noncurrent Liabilities
Restructuring Cost and Reserve [Line Items]
Restructuring liabilities	41		41	$ 41
Severance
Restructuring Cost and Reserve [Line Items]
Payments for severance	$ 18		$ 89