Income Taxes (Tables)

6 Months Ended

Sep. 30, 2016

Income Tax Disclosure [Abstract]

Factors Causing Variation in Effective Tax Rate From US Federal Statutory Rate

The differences that caused our effective income tax rates to vary from the 35% U.S. federal statutory rate for income taxes were as follows:

	Six Months Ended September 30,
	2016			2015
	(in millions)
Income tax benefit at the federal statutory rate	$	94		$	202
Effect of:
State income taxes, net of federal income tax effect	5			16
State law changes, net of federal income tax effect	3			25
Tax benefit from organizational restructuring	42			—
Change in federal and state valuation allowance	(314		)	(275		)
Other, net	(5		)	3
Income tax expense	$	(175	)	$	(29	)
Effective income tax rate	(65.1		)%	(5.0		)%