Stockholders' Equity - Narrative (Details)	1 Months Ended	3 Months Ended			6 Months Ended
	Jul. 31, 2015 $ / shares	Sep. 30, 2016 USD ($) vote $ / shares shares	Sep. 30, 2015 USD ($) $ / shares	Jun. 30, 2015 $ / shares	Sep. 30, 2016 USD ($) vote $ / shares shares	Sep. 30, 2015 USD ($) $ / shares	Oct. 27, 2016 USD ($)
Equity, Class of Treasury Stock [Line Items]
Share of common stock outstanding, vote on proposals | vote		1			1
Dividends declared per common share (in dollars per share) | $ / shares	$ 0.28	$ 0.28	$ 0.28	$ 0.24	$ 0.56	$ 0.52
Stock repurchased during the period (shares) | shares		0			0
Stock repurchased during the period		$ 0			$ 0
Authorized amount available for future repurchases		1,000,000,000			1,000,000,000
Net foreign currency translation gains (losses)		1,000,000			(65,000,000)
Translation gain (loss) attributable to redeemable noncontrolling interest			$ (20,000,000)			$ 30,000,000
Reclassified to income statement, net of income tax expense of nil and nil		0	0		20,000,000	0
Net actuarial losses attributable to redeemable noncontrolling interest		0	$ 0		1,000,000	$ 6,000,000
Subsequent Event
Equity, Class of Treasury Stock [Line Items]
Authorized stock repurchase amount (shares)							$ 4,000,000,000
Foreign Currency Translation Adjustments, Net of Tax
Equity, Class of Treasury Stock [Line Items]
Net foreign currency translation gains (losses)		$ 1,000,000			$ (66,000,000)