Employee Benefit Plan (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Employee Benefit Plan Narrative Details
401(k) Savings Plan	In April 1991, the Company adopted a 401(k) savings plan (the "Savings Plan") covering substantially all of its U.S. employees. Eligible employees may contribute to the Savings Plan from their compensation up to the maximum allowed by the Internal Revenue Service. In January 2007, the Company reactivated the employer matching contribution. The matching contribution is 100% of each employee's contributions up to $1,500, then 50% of the employee's contributions, not to exceed $3,000 per annum, in aggregate.
Matching 401(k) expense	$ 1.6	$ 0.9	$ 0.7

Description of benefits provided to former or inactive employees, their beneficiaries, and covered dependents after employment but before retirement, except for: a) benefits provided through a pension or postretirement benefit plan, b) individual deferred compensation arrangements, c) termination benefits pertaining to exit or disposal activities, and d) stock compensation plans. Benefits may be provided in cash or in kind and may be paid as a result of disability, layoff, death, or other event.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 712
-SubTopic 10
-Section 15
-Paragraph 3
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6410066&loc=d3e79194-111664

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Balance Type:	na
Period Type:	duration