Summary of Open Tax Years (Detail)	6 Months Ended
	Sep. 30, 2013
Minimum | U.S. federal
Income Tax Examination [Line Items]
Open tax years	2008
Minimum | States
Income Tax Examination [Line Items]
Open tax years	2008
Maximum | U.S. federal
Income Tax Examination [Line Items]
Open tax years	2012
Maximum | States
Income Tax Examination [Line Items]
Open tax years	2012