Annual report pursuant to Section 13 and 15(d)

Stockholders' Equity - Grants outside of 2000 Plan (Details)

Stockholders' Equity - Grants outside of 2000 Plan (Details) - USD ($) $ / shares in Units, $ in Millions						12 Months Ended
	Apr. 22, 2016	Dec. 31, 2015	Aug. 28, 2015	May. 06, 2014	Oct. 31, 2013	Mar. 31, 2016	Mar. 31, 2015	Mar. 31, 2014
Class of Stock [Line Items]
Options outstanding (in shares)						500,000	700,000	700,000
Restricted stock units outstanding (in shares)						300,000	100,000	100,000
Stockholder Rights Plan
Preferred stock, par value (in dollars per share)						$ 0.001	$ 0.001
At-the-market Offering Program and Underwritten Offering of Common Stock
Common stock sold (in shares)		6,900,000		900,000
Net proceeds from sale of the common stock, after deducting fees and other offering expenses (in dollars)	$ 13.1	$ 12.7		$ 29.8
Share Price				$ 34.00
March 2012
At-the-market Offering Program and Underwritten Offering of Common Stock
Class of Warrant or Right Number of Warrants Exercised					4,700,000
Proceeds from unsolicited exercise of 2012 warrants					$ 6.0
Maximum
At-the-market Offering Program and Underwritten Offering of Common Stock
Aggregate offering price for at-the-market offering program			$ 30.0
Stock options
Class of Stock [Line Items]
Options outstanding (in shares)						467,631	658,170
Options granted (in shares)						29,225
Stock options \| Non-qualified stock options
Class of Stock [Line Items]
Options outstanding (in shares)						148,229
Options granted (in shares)							12,500
Stock options \| Executive Vice President and Chief Executive Officer \| Non-qualified stock options
Class of Stock [Line Items]
Options outstanding (in shares)						100,000
Stock options \| Executive Vice President of Sales and Marketing \| Non-qualified stock options
Class of Stock [Line Items]
Options outstanding (in shares)						42,500
Stock options \| Vice President of Operations \| Non-qualified stock options
Class of Stock [Line Items]
Options outstanding (in shares)						5,729
Non-qualified stock options issued prior to Fiscal 2015
Class of Stock [Line Items]
Options granted (in shares)							142,500
Restricted stock units
Class of Stock [Line Items]
Restricted stock units outstanding (in shares)						2,343
Options granted (in shares)							2,343
Restricted stock units \| Non-qualified stock options
Class of Stock [Line Items]
Options outstanding (in shares)						2,343
Restricted stock units \| Vice President of Operations \| Non-qualified stock options
Class of Stock [Line Items]
Restricted stock units outstanding (in shares)						2,343
Series B Junior Participating Preferred Stock
Stockholder Rights Plan
Preferred share purchase rights period						30 days
Preferred stock conversion basis						0.001
Preferred stock, par value (in dollars per share)						$ 0.001
Purchase price (in dollars per share)						$ 8.76
Period following public announcement of beneficial ownership acquired by various persons resulting in rights becoming exercisable						10 days
Period following commencement of tender offer or exchange offer that would result in acquisition of beneficial ownership various persons resulting in rights becoming exercisable						10 days
Preferred stock dividend minimum if declared						$ 1.00
Preferred stock rights ratio over common stock						1,000
Series B Junior Participating Preferred Stock \| Minimum
Stockholder Rights Plan
Beneficial ownership of common stock (as a percent)						4.99%