Stock-Based Compensation (Details) (USD $)	12 Months Ended
	Mar. 31, 2013 item	Mar. 31, 2012	Mar. 31, 2011
Additional disclosures
Weighted average grant-date fair value of non-vested shares (in dollars per share)	$ 4.09	$ 5.27
Weighted average grant-date fair value of shares granted (in dollars per share)	$ 2.78
Weighted average grant-date fair value of shares vested (in dollars per share)	$ 5.32
Weighted average grant-date fair value of shares forfeited (in dollars per share)	$ 5.69
Stock options
Major components of stock based compensation expense
Stock-based compensation expense	$ 1,640,000	$ 1,330,000	$ 566,000
Stock-based compensation, additional disclosure
Number of plans with outstanding stock options	4
Shares authorized for grant	4,000,000
Expiration period	10 years
Number of plans that reserved shares of common stock for issuance to executives and key employees	4
Options
Outstanding at the beginning of the period (in shares)	1,769,000
Granted (in shares)	333,000
Exercised (in shares)	(50,000)
Forfeited (in shares)	(16,000)
Expired (in shares)	(85,000)
Outstanding at the end of the period (in shares)	1,951,000	1,769,000
Exercisable (in shares)	1,260,000
Weighted-Average Exercise Price
Outstanding at the beginning of the period (in dollars per share)	$ 13.43
Granted (in dollars per share)	$ 4.70
Exercised (in dollars per share)	$ 2.18
Forfeited (in dollars per share)	$ 9.07
Expired (in dollars per share)	$ 23.76
Outstanding at the end of the period (in dollars per share)	$ 11.84	$ 13.43
Exercisable (in dollars per share)	$ 14.61
Additional disclosures
Remaining weighted average contractual life of options exercisable	5 years
Remaining weighted average contractual life of options outstanding	6 years 4 months 24 days
Total estimated fair value of shares vested	1,700,000	600,000	200,000
Intrinsic value of stock options exercised	200,000	1,000,000	600,000
Stock options | Cost of sales
Major components of stock based compensation expense
Stock-based compensation expense	710,000	542,000	216,000
Stock options | Selling, general and administrative expenses
Major components of stock based compensation expense
Stock-based compensation expense	872,000	788,000	350,000
Stock options | Research and development
Major components of stock based compensation expense
Stock-based compensation expense	58,000
Stock options | Maximum
Stock-based compensation, additional disclosure
Vesting period	3 years
Stock options | Minimum
Stock-based compensation, additional disclosure
Vesting period	1 year
Restricted stock
Major components of stock based compensation expense
Stock-based compensation expense	1,748,000	769,000	329,000
Additional disclosures
Weighted average grant-date fair value of non-vested shares (in dollars per share)	$ 7.15	$ 8.25
Restricted stock | Cost of sales
Major components of stock based compensation expense
Stock-based compensation expense	445,000	81,000
Restricted stock | Selling, general and administrative expenses
Major components of stock based compensation expense
Stock-based compensation expense	1,303,000	688,000	329,000
Chief executive officer | Stock options | Awards that vest on June 30, 2014
Stock-based compensation, additional disclosure
Vesting percentage	50.00%
Chief executive officer | Stock options | Awards that vest on June 30th, 2015
Stock-based compensation, additional disclosure
Vesting percentage	50.00%
2011 Incentive Plan
Stock-based compensation, additional disclosure
Shares authorized for grant	4,800,000
Prior Plans | Stock options
Stock-based compensation, additional disclosure
Shares authorized for grant	800,000
LTIP Plans
Major components of stock based compensation expense
Stock-based compensation expense	1,211,000	976,000	888,000
LTIP Plans | Cost of sales
Major components of stock based compensation expense
Stock-based compensation expense	356,000	176,000
LTIP Plans | Selling, general and administrative expenses
Major components of stock based compensation expense
Stock-based compensation expense	725,000	800,000	888,000
LTIP Plans | Research and development
Major components of stock based compensation expense
Stock-based compensation expense	$ 130,000