Summary of Significant Accounting Policies (Details 2) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Mar. 31, 2013 step	Mar. 31, 2012
Inventories
Raw materials	$ 102,238	$ 122,072
Work/ Contracts in process	82,454	53,018
Finished goods	130,372	83,405
Net inventories	$ 315,064	$ 258,495
Accounting for Goodwill and Identifiable Intangible Assets
Number of steps involved in the process of impairment testing	2
Minimum | Stock options
Stock-Based Compensation
Minimum vesting period (in years)	1 year
Maximum | Stock options
Stock-Based Compensation
Minimum vesting period (in years)	3 years