Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Mar. 31, 2018		Mar. 31, 2017	Mar. 31, 2016
Income Statement [Abstract]
Revenue	$ 593,749		$ 445,304	$ 329,543
Costs and expenses:
Cost of revenue	98,581		70,627	50,419
Research and development	75,297		66,386	49,759
Selling, general and administrative	262,734		218,153	164,261
Costs and Expenses, Total	436,612		355,166	264,439
Income from operations	157,137		90,138	65,104
Other income:
Investment income, net	3,688		1,554	395
Other (expense) income, net	(388)		(349)	339
Nonoperating Income (Expense), Total	3,300		1,205	734
Income before income taxes	160,437		91,343	65,838
Income tax provision	48,267	[1],[2]	39,227	27,691
Net income	$ 112,170		$ 52,116	$ 38,147
Basic net income per share	$ 2.54		$ 1.21	$ 0.90
Basic weighted average shares outstanding	44,153		43,238	42,204
Diluted net income per share	$ 2.45		$ 1.17	$ 0.85
Diluted weighted average shares outstanding	45,849		44,658	44,895

[1] In the first quarter of fiscal 2018, the Company adopted Accounting Standards Update No. 2016-09, Improvements to Employee Share-Based Payment Accounting, which requires that all excess tax benefits and tax deficiencies related share-based compensation arrangements be recognized as income tax benefit or expense, instead of in stockholders’ equity as previous guidance required. The income tax benefit for the year ended March 31, 2018 included excess tax benefits of $31.0 million. These recognized excess tax benefits resulted from restricted stock units that vested or stock options that were exercised during the year ended March 31, 2018.

[2] On December 22, 2017, the Tax Cuts and Jobs Act, or Tax Reform Act, was enacted into law. This new law, among other items, reduces the U.S. federal statutory corporate income tax rate from 35% to 21% effective January 1, 2018. During the year ended March 31, 2018, the Company recorded tax expense adjustments for $21.4 million related to the revaluation of its deferred taxes due to a reduction of the U.S. federal statutory corporate income tax rate.