Consolidated Statements of Convertible Preferred Stock and Stockholders' Equity (Deficit) (USD $) In Thousands, except Share data, unless otherwise specified	Total	Convertible Preferred Stock	Common Stock	Additional Paid-in Capital	Accumulated Deficit
Beginning Balance at Mar. 31, 2011	$ (31,438)	$ 81,373	$ 1	$ 4,424	$ (35,863)
Beginning Balance (in shares) at Mar. 31, 2011		12,281,553	464,994
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Reclassification of convertible preferred stock warrant liability	(431)			(431)
Issuance of common stock upon exercise of stock options (in shares)			18,248
Issuance of common stock upon exercise of stock options	50			50
Stock-based compensation	801			801
Excess tax benefit from stock-based compensation	150			150
Dividends paid	(13,550)				(13,550)
Net Income	10,036				10,036
Ending Balance at Mar. 31, 2012	(34,984)	81,373	1	4,392	(39,377)
Ending Balance (in shares) at Mar. 31, 2012		12,281,553	483,242
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Reclassification of convertible preferred stock warrant liability	2,170			2,170
Conversion of convertible preferred stock into common stock upon consummation of IPO (in shares)		(12,281,553)	15,221,571
Conversion of convertible preferred stock into common stock upon consummation of IPO	81,373	(81,373)	15	81,358
Shares issued upon consummation of IPO (in shares)			950,000
Shares issued upon consummation of IPO	11,146		1	11,145
Shares repurchased and retired (in shares)			(500,000)
Shares repurchased and retired	(19,125)			(19,125)
Issuance of common stock upon exercise of stock options (in shares)			631,010
Issuance of common stock upon exercise of stock options	4,073			4,073
Stock-based compensation	1,064			1,064
Excess tax benefit from stock-based compensation	8,113			8,113
Net exercise of warrant to purchase shares of common stock			63,193
Net Income	11,252				11,252
Ending Balance at Mar. 31, 2013	65,082	0	17	93,190	(28,125)
Ending Balance (in shares) at Mar. 31, 2013		0	16,849,016
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Repurchase of stock options for cash	(602)			(602)
Issuance of common stock upon exercise of stock options (in shares)	186,919		190,776
Issuance of common stock upon exercise of stock options	1,958			1,958
Stock-based compensation	465			465
Excess tax benefit from stock-based compensation	2,118			2,118	0
Net Income	15,289				15,289
Ending Balance at Mar. 31, 2014	$ 84,912	$ 0	$ 17	$ 97,731	$ (12,836)
Ending Balance (in shares) at Mar. 31, 2014		0	17,039,792