Commitments and Contingencies - Additional Information (Detail) (USD $)	12 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2011
Commitments and Contingencies Disclosure [Line Items]
Fair value of contingent liability	$ 5,087,000	$ 8,213,000
Contractual non-compliance liabilities incurred by Simena	246,000	700,000
Total rent expense under non-cancelable operating leases	5,700,000	5,600,000	5,600,000
Simena LLC
Commitments and Contingencies Disclosure [Line Items]
Fair value of contingent liability	8,000,000
Contractual non-compliance liabilities incurred by Simena	1,600,000
Simena LLC | Present value of future consideration
Commitments and Contingencies Disclosure [Line Items]
Fair value of contingent liability	5,100,000
Contractual non-compliance liabilities incurred by Simena	$ 246,000