Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Treasury Stock	Additional Paid in Capital	Accumulated Deficit	Accumulated Other Comprehensive (Loss) Income
Beginning Balance at Mar. 31, 2014	$ 168,353	$ 411	$ (16,554)	$ 436,136	$ (250,910)	$ (730)
Beginning Balance (in shares) at Mar. 31, 2014		39,916,328	1,206,367
Restricted stock units issued		$ 5		(5)
Restricted stock units issued (in shares)		543,420
Stock options exercised	10,927	$ 9		10,918
Stock options exercised (in shares)		911,553
Stock issued under employee stock purchase plan	795			795
Stock issued under employee stock purchase plan (in shares)		39,095
Stock issued to directors	76			76
Stock issued to directors (in shares)		1,954
Return of common stock to pay withholding taxes on restricted stock	(2,805)	$ (12)	$ (2,793)
Return of common stock to pay withholding taxes on restricted stock (in shares)		(76,577)	76,577
Stock compensation expense	16,520			16,520
Excess tax benefit from stock-based awards	606			606
Other comprehensive income (loss)	(16,600)					(16,600)
Net income	113,688				113,688
Ending Balance at Mar. 31, 2015	291,560	$ 413	$ (19,347)	465,046	(137,222)	(17,330)
Ending Balance (in shares) at Mar. 31, 2015		41,335,773	1,282,944
Restricted stock units issued		$ 5		(5)
Restricted stock units issued (in shares)		507,471
Stock options exercised	9,771	$ 8		9,763
Stock options exercised (in shares)		829,385
Stock issued under employee stock purchase plan	1,135			1,135
Stock issued under employee stock purchase plan (in shares)		16,772
Stock issued to directors	65			65
Stock issued to directors (in shares)		774
Return of common stock to pay withholding taxes on restricted stock	(7,313)		$ (7,313)
Return of common stock to pay withholding taxes on restricted stock (in shares)		(93,947)	93,947
Stock compensation expense	29,053			29,053
Excess tax benefit from stock-based awards	3,567			3,567
Other comprehensive income (loss)	2,790					2,790
Net income	38,147				38,147
Ending Balance at Mar. 31, 2016	$ 368,775	$ 426	$ (26,660)	508,624	(99,075)	(14,540)
Ending Balance (in shares) at Mar. 31, 2016	42,596,228	42,596,228	1,376,891
Restricted stock units issued		$ 5		(5)
Restricted stock units issued (in shares)		502,417
Stock options exercised	$ 10,660	$ 8		10,652
Stock options exercised (in shares)	755,000	754,893
Stock issued under employee stock purchase plan	$ 1,720			1,720
Stock issued under employee stock purchase plan (in shares)		18,288
Stock issued to directors	67			67
Stock issued to directors (in shares)		564
Return of common stock to pay withholding taxes on restricted stock	(20,105)	$ (2)	$ (20,103)
Return of common stock to pay withholding taxes on restricted stock (in shares)		(199,104)	199,104
Stock compensation expense	32,866			32,866
Excess tax benefit from stock-based awards	12,038			12,038
Other comprehensive income (loss)	(6,066)					(6,066)
Net income	52,116				52,116
Ending Balance at Mar. 31, 2017	$ 452,071	$ 437	$ (46,763)	$ 565,962	$ (46,959)	$ (20,606)
Ending Balance (in shares) at Mar. 31, 2017	43,673,286	43,673,286	1,575,995