Basis of Presentation and Summary of Significant Accounting Policies - Effects of the Corrections on the Financial Statements (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended										12 Months Ended
	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013		Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012		Mar. 31, 2014	Mar. 31, 2013		Mar. 31, 2012		Mar. 31, 2011
Net sales	$ 60,057	$ 46,419	$ 58,310	$ 39,318	$ 52,092		$ 36,319	$ 46,651	$ 34,410		$ 204,104	$ 169,472		$ 141,481
Cost of sales	39,037	28,228	36,932	24,278	32,027		23,267	28,786	20,486		128,475	104,566		85,877
Gross profit	21,020	18,191	21,378	15,040	20,065		13,052	17,865	13,924		75,629	64,906		55,604
Selling, general and administrative expenses		13,421	12,575	11,364	13,024		10,687	11,539	10,211		49,509	45,461		37,790
Income from operations		4,770	8,803	3,676	7,041		2,365	6,326	3,713		26,120	19,445		17,814
Interest expense		(80)	(104)	(71)	(48)		(40)	(40)	(40)		(335)	(168)		(161)
Other income (expense), net		30	32	26	(29)		31	36	49		41	87		(1,076)
Income before provision for income taxes	8,744	4,720	8,731	3,631	6,964		2,356	6,322	3,722		25,826	19,364		16,577
Provision for income taxes		1,951	3,511	1,459	3,099		934	2,558	1,521		10,537	8,112		6,541
Net Income	5,128	2,769	5,220	2,172	3,865		1,422	3,764	2,201		15,289	11,252		10,036
Stock-based compensation											465	1,064		801
Net income attributable to common stockholders											15,289	11,252		303
Earnings per share
-Basic (in dollars per share)	$ 0.30	$ 0.16	$ 0.31	$ 0.13	$ 0.22		$ 0.08	$ 0.22	$ 0.13		$ 0.90	$ 0.66		$ 0.65
-Diluted (in dollars per share)	$ 0.29	$ 0.16	$ 0.30	$ 0.13	$ 0.22		$ 0.08	$ 0.21	$ 0.12		$ 0.88	$ 0.64		$ 0.27
Weighted average shares of common stock outstanding used in computing earnings per share
-Basic (shares)	17,005,472	16,937,139	16,896,227	16,869,557	17,262,253		17,249,536	17,070,327	16,936,007		16,926,827	17,129,334		469,089
-Diluted (shares)	17,425,573	17,398,006	17,392,447	17,353,222	17,724,131		17,781,720	17,702,516	17,600,908		17,412,548	17,707,839		1,111,088
Accounts receivable	18,324				18,756	[1]					18,324	18,756	[1]
Deferred tax assets	3,312				3,140						3,312	3,140
Total current assets	61,710				47,611						61,710	47,611
Total assets	103,641				89,535						103,641	89,535
Accrued liabilities	10,680				12,191	[1]					10,680	12,191	[1]
Accrued expenses and other non-current liabilities											194	8,194	[1]	27	[1]
Total current liabilities	17,824				16,533						17,824	16,533
Liabilities	18,729				24,453						18,729	24,453
Accumulated deficit	(12,836)				(28,125)						(12,836)	(28,125)		(39,377)		(35,863)
Additional paid-in capital	97,731				93,190						97,731	93,190		4,392		4,424
Stock-based compensation											465	1,064		801
Total stockholders’ equity	84,912				65,082						84,912	65,082		(34,984)		(31,438)
Total liabilities and stockholders’ equity	103,641				89,535						103,641	89,535
Deferred taxes											493	177		442
Accounts receivable											432	(7,580)	[1]	(3,114)	[1]
Change in fair value of convertible preferred stock warrant liability											0	13		1,208
Reported
Net sales		46,177	58,650	39,040	52,715		36,283	46,686	34,293			169,977		141,304
Cost of sales		27,951	36,749	24,278	32,027		23,267	28,786	20,486			104,566		85,877
Gross profit		18,226	21,901	14,762	20,688		13,016	17,900	13,807			65,411		55,427
Selling, general and administrative expenses		13,421	12,538	11,327	13,024		10,687	11,539	10,211			45,461		37,495
Income from operations		4,805	9,363	3,435	7,664		2,329	6,361	3,596			19,950		17,932
Interest expense		(80)	(104)	(71)	(48)		(40)	(40)	(40)			(168)		(161)
Other income (expense), net		30	32	26	(29)		31	36	49			87		(1,594)
Income before provision for income taxes		4,755	9,291	3,390	7,587		2,320	6,357	3,605			19,869		16,177
Provision for income taxes		1,966	3,739	1,361	3,353		919	2,572	1,474			8,318		6,588
Net Income		2,789	5,552	2,029	4,234		1,401	3,785	2,131			11,551		9,589
Stock-based compensation														506
Net income attributable to common stockholders														290
Earnings per share
-Basic (in dollars per share)		$ 0.16	$ 0.33	$ 0.12	$ 0.25		$ 0.08	$ 0.22	$ 0.13			$ 0.67		$ 0.62
-Diluted (in dollars per share)		$ 0.16	$ 0.32	$ 0.12	$ 0.24		$ 0.08	$ 0.21	$ 0.12			$ 0.65		$ 0.26
Weighted average shares of common stock outstanding used in computing earnings per share
-Basic (shares)		16,937,139	16,896,227	16,869,557	17,262,253		17,249,536	17,070,327	16,936,007			17,129,334		469,089
-Diluted (shares)		17,398,006	17,392,447	17,353,222	17,724,131		17,781,720	17,702,516	17,600,908			17,707,839		1,111,088
Accounts receivable					20,015	[1]						20,015	[1]
Deferred tax assets					2,558							2,558
Total current assets					48,288							48,288
Total assets					90,212							90,212
Accrued liabilities					12,021	[1]						12,021	[1]
Accrued expenses and other non-current liabilities									(168)	[1]		8,254	[1]
Total current liabilities					16,363							16,363
Liabilities					24,283							24,283
Accumulated deficit					(27,278)							(27,278)		(38,829)		(34,868)
Additional paid-in capital					93,190							93,190		4,392		4,719
Stock-based compensation														506
Total stockholders’ equity					65,929							65,929		(34,436)		(30,148)
Total liabilities and stockholders’ equity					90,212							90,212
Deferred taxes												383		489
Accounts receivable												(8,145)	[1]	(2,742)	[1]
Change in fair value of convertible preferred stock warrant liability														1,726
Correction
Net sales		242	(340)	278	(623)		36	(35)	117			(505)		177
Cost of sales		277	183	0	0		0	0	0			0		0
Gross profit		(35)	(523)	278	(623)		36	(35)	117			(505)		177
Selling, general and administrative expenses		0	37	37	0		0	0	0			0		295
Income from operations		(35)	(560)	241	(623)		36	(35)	117			(505)		(118)
Interest expense		0	0	0	0		0	0	0			0		0
Other income (expense), net		0	0	0	0		0	0	0			0		518
Income before provision for income taxes		(35)	(560)	241	(623)		36	(35)	117			(505)		400
Provision for income taxes		(15)	(228)	98	(254)		15	(14)	47			(206)		(47)
Net Income		(20)	(332)	143	(369)		21	(21)	70			(299)		447
Stock-based compensation														295
Net income attributable to common stockholders														13
Earnings per share
-Basic (in dollars per share)		$ 0.00	$ (0.02)	$ 0.01	$ (0.02)		$ 0.00	$ 0.00	$ 0.00			$ (0.01)		$ 0.03
-Diluted (in dollars per share)		$ 0.00	$ (0.02)	$ 0.01	$ (0.02)		$ 0.00	$ 0.00	$ 0.00			$ (0.01)		$ 0.01
Weighted average shares of common stock outstanding used in computing earnings per share
-Basic (shares)		16,937,139	16,896,227	16,869,557	17,262,253		17,249,536	17,070,327	16,936,007
-Diluted (shares)		17,398,006	17,392,447	17,353,222	17,724,131		17,781,720	17,702,516	17,600,908
Accounts receivable					(1,259)	[1]						(1,259)	[1]
Deferred tax assets					582							582
Total current assets					(677)							(677)
Total assets					(677)							(677)
Accrued liabilities					170	[1]						170	[1]
Accrued expenses and other non-current liabilities												(60)	[1]	195	[1]
Total current liabilities					170							170
Liabilities					170							170
Accumulated deficit					(847)							(847)		(548)		(995)
Additional paid-in capital					0							0		0		(295)
Stock-based compensation														295
Total stockholders’ equity					(847)							(847)		(548)		(1,290)
Total liabilities and stockholders’ equity					(677)							(677)
Deferred taxes												(206)		(47)
Accounts receivable												565	[1]	(372)	[1]
Change in fair value of convertible preferred stock warrant liability														$ (518)

[1] Includes an immaterial reclassification between accounts receivable and accrued liabilities.