Summary of Open Tax Years (Detail)	6 Months Ended
	Sep. 30, 2015
Minimum | States
Income Tax Examination [Line Items]
Open tax years	2011
Minimum | U.S. federal
Income Tax Examination [Line Items]
Open tax years	2011
Maximum | States
Income Tax Examination [Line Items]
Open tax years	2014
Maximum | U.S. federal
Income Tax Examination [Line Items]
Open tax years	2014