Stockholders' Equity (Details) - USD ($) $ in Thousands	3 Months Ended
	Jun. 30, 2018	Jul. 01, 2017
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance, common stock, shares	9,044,858
Ending balance, common stock, shares	9,061,306
Beginning balance	$ 457,106
Stock option exercises, amount	(2,168)
Stock-based compensation	599
Net income	19,691	$ 11,753
Other Comprehensive Income (Loss)	5
Ending balance	475,687
Pre-tax unrealized gain (loss) on available-for-sale investments	$ 6	$ (833)
Common Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance, common stock, shares	9,044,858
Stock option exercises, shares	16,448
Ending balance, common stock, shares	9,061,306
Beginning balance	$ 90
Stock option exercises, amount	1
Stock-based compensation	0
Net income	0
Other Comprehensive Income (Loss)	0
Ending balance	91
Additional paid-in capital
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	246,197
Stock option exercises, amount	(2,169)
Stock-based compensation	599
Net income	0
Other Comprehensive Income (Loss)	0
Ending balance	244,627
Retained earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	209,381
Stock option exercises, amount	0
Stock-based compensation	0
Net income	19,691
Other Comprehensive Income (Loss)	0
Ending balance	231,147
Accumulated other comprehensive income
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	1,438
Stock option exercises, amount	0
Stock-based compensation	0
Net income	0
Other Comprehensive Income (Loss)	5
Ending balance	(178)
Accounting Standards Update 2016-01 [Member]
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets	1,621
Accounting Standards Update 2016-01 [Member] | Reclassification out of Accumulated Other Comprehensive Income [Domain]
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets	(1,621)
Difference between Revenue Guidance in Effect before and after Topic 606 [Member]
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets	$ 454