Stockholder's Equity Stock Options Outstanding And Exercisable (Details) - USD ($)	12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015	Mar. 31, 2014
Options Outstanding, Number of Shares	4,462,412	4,793,266	5,327,907	6,002,382
Options Outstanding, Weighted-Average Exercise Price Per Share	$ 7.52	$ 6.29	$ 5.19	$ 4.14
Options Exercisable, Number of Shares	3,191,879
Options Exercisable, Weighted-Average Exercise Price Per Share	$ 6.47
$0.55 - $4.60
Range of Exercise Prices, Minimum	0.55
Range of Exercise Prices, Maximum	$ 4.60
Options Outstanding, Number of Shares	912,189
Options Outstanding, Weighted-Average Exercise Price Per Share	$ 1.91
Options Outstanding, Weighted-Average Remaining Contractual Term (in years)	2 years
Options Outstanding, Aggregate Intrinsic Value	$ 12,168,894
Options Exercisable, Number of Shares	912,189
Options Exercisable, Weighted-Average Exercise Price Per Share	$ 1.91
Options Exercisable, Aggregate Intrinsic Value	$ 12,168,894
$5.87 - $6.86
Range of Exercise Prices, Minimum	$ 5.87
Range of Exercise Prices, Maximum	$ 6.86
Options Outstanding, Number of Shares	1,139,300
Options Outstanding, Weighted-Average Exercise Price Per Share	$ 6.48
Options Outstanding, Weighted-Average Remaining Contractual Term (in years)	6 years 252 days
Options Outstanding, Aggregate Intrinsic Value	$ 9,996,307
Options Exercisable, Number of Shares	863,274
Options Exercisable, Weighted-Average Exercise Price Per Share	$ 6.35
Options Exercisable, Aggregate Intrinsic Value	$ 7,680,449
$7.52 - $9.21
Range of Exercise Prices, Minimum	$ 7.52
Range of Exercise Prices, Maximum	$ 9.21
Options Outstanding, Number of Shares	920,268
Options Outstanding, Weighted-Average Exercise Price Per Share	$ 8.43
Options Outstanding, Weighted-Average Remaining Contractual Term (in years)	7 years 144 days
Options Outstanding, Aggregate Intrinsic Value	$ 6,277,429
Options Exercisable, Number of Shares	503,564
Options Exercisable, Weighted-Average Exercise Price Per Share	$ 8.47
Options Exercisable, Aggregate Intrinsic Value	$ 3,414,760
$9.35 - $10.50
Range of Exercise Prices, Minimum	$ 9.35
Range of Exercise Prices, Maximum	$ 10.50
Options Outstanding, Number of Shares	904,935
Options Outstanding, Weighted-Average Exercise Price Per Share	$ 9.73
Options Outstanding, Weighted-Average Remaining Contractual Term (in years)	6 years 216 days
Options Outstanding, Aggregate Intrinsic Value	$ 4,998,813
Options Exercisable, Number of Shares	758,640
Options Exercisable, Weighted-Average Exercise Price Per Share	$ 9.71
Options Exercisable, Aggregate Intrinsic Value	$ 4,206,928
$10.86 - $15.40
Range of Exercise Prices, Minimum	$ 10.86
Range of Exercise Prices, Maximum	$ 15.40
Options Outstanding, Number of Shares	585,720
Options Outstanding, Weighted-Average Exercise Price Per Share	$ 13.48
Options Outstanding, Weighted-Average Remaining Contractual Term (in years)	8 years 288 days
Options Outstanding, Aggregate Intrinsic Value	$ 1,043,018
Options Exercisable, Number of Shares	154,212
Options Exercisable, Weighted-Average Exercise Price Per Share	$ 11.68
Options Exercisable, Aggregate Intrinsic Value	$ 551,242
$0.55 - $15.40
Range of Exercise Prices, Minimum	$ 0.55
Range of Exercise Prices, Maximum	$ 15.40
Options Outstanding, Number of Shares	4,462,412
Options Outstanding, Aggregate Intrinsic Value	$ 34,484,461
Options Exercisable, Number of Shares	3,191,879
Options Exercisable, Aggregate Intrinsic Value	$ 28,022,273