Income Taxes (Tables)

3 Months Ended

Jun. 30, 2019

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 differ from the 21% U.S. federal statutory rate for income taxes were as follows:

	Three Months Ended June 30,
	2019			2018
	(in millions)
Income tax benefit (expense) at the federal statutory rate	$	29		$	(46	)
Effect of:
State income taxes, net of federal income tax effect	5			(15		)
State law changes, net of federal income tax effect	—			24
Increase deferred tax liability for organizational restructuring	—			(13		)
Credit for increasing research activities	4			—
Change in federal and state valuation allowance	(14		)	6
Other, net	(2		)	(3		)
Income tax benefit (expense)	$	22		$	(47	)
Effective income tax rate	16.2		%	21.4		%