Redeemable Noncontrolling Interests - Narrative (Details) $ in Millions	6 Months Ended
	Sep. 30, 2015 € / shares	Sep. 30, 2015 USD ($)	Mar. 31, 2015 USD ($)
Noncontrolling Interest [Abstract]
NCI, annual compensation per share (in euros per share)	€ 0.83
NCI, put right redemption price per share (in euros per share)	€ 22.99
NCI, put right value, interest rate spread (as a percent)		5.00%
Put right specified in domination agreement exercise period	2 months
Redeemable noncontrolling interests | $		$ 1,410	$ 1,386
Redeemable NCI, maximum redemption value | $		$ 1,260	$ 1,210
NCI, ownership percentage (as a percent)		76.00%	76.00%