Summary of Interim Financial Information (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended																12 Months Ended
	Mar. 31, 2013		Dec. 30, 2012		Sep. 30, 2012		Jul. 01, 2012		Mar. 31, 2012		Jan. 01, 2012		Oct. 02, 2011		Jul. 03, 2011		Mar. 31, 2013		Mar. 31, 2012		Mar. 31, 2011
Quarterly Financial Information [Line Items]
Net sales	$ 572,117		$ 557,320		$ 554,212		$ 593,910		$ 592,754		$ 574,246		$ 547,140		$ 569,229		$ 2,277,559		$ 2,283,369		$ 1,964,462
Gross profit	139,013		143,698		138,339		148,306		145,463		130,876		114,395		121,971		569,356		512,705		449,844
Operating earnings	56,991	[1]	59,737	[1]	62,885	[1]	70,255	[1]	65,879	[2]	53,777	[2]	42,440	[2]	48,715	[2]	249,868	[1],[3]	210,811	[2],[3]	183,814	[3]
Net earnings	37,706		38,677		43,011		45,564		45,323		36,859		28,289		33,496		164,958		143,967		113,426
Net earnings attributable to EnerSys stockholders	$ 37,730		$ 39,184		$ 43,790		$ 45,804		$ 45,359		$ 36,859		$ 28,289		$ 33,496		$ 166,508		$ 144,003		$ 113,426
Net earnings per common share attributable to EnerSys stockholders-basic	$ 0.79		$ 0.81		$ 0.91		$ 0.96		$ 0.95		$ 0.77		$ 0.57		$ 0.67		$ 3.47		$ 2.95		$ 2.30
Net earnings per common share attributable to EnerSys stockholders-diluted	$ 0.77		$ 0.80		$ 0.90		$ 0.95		$ 0.94		$ 0.77		$ 0.57		$ 0.66		$ 3.42		$ 2.93		$ 2.27

[1] Included in Operating earnings were restructuring charges of $370, $1,295, $3,776 and $1,723 for the first, second, third and fourth quarters of fiscal 2013, respectively.

[2] Included in Operating earnings were restructuring charges of $410, $902, $1,440 and $2,236 for the first, second, third and fourth quarters of fiscal 2012, respectively. Operating earnings also included a legal proceedings settlement income of $900, in the second quarter of fiscal 2012.

[3] The Company does not allocate interest expense or other (income) expense to the reportable segments.