Stockholders' Equity (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Dec. 30, 2017	Dec. 31, 2016	Dec. 30, 2017	Dec. 31, 2016
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets		$ 69		$ 69
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance, common stock, shares				8,994,968
Beginning balance				$ 394,408
Stock option exercises, amount				(1,104)
Stock-based compensation				1,918
Net income		$ 21,427	$ 12,283	39,362	$ 27,067
Other comprehensive loss	[1]			$ 919
Ending balance, common stock, shares		9,035,294		9,035,294
Ending balance		$ 435,572		$ 435,572
Pre-tax unrealized loss on available-for-sale investments				$ 1,500
Common Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance, common stock, shares				8,994,968
Beginning balance				$ 90
Stock option exercises, shares				40,326
Stock option exercises, amount				$ 0
Stock-based compensation				0
Net income				0
Other comprehensive loss				$ 0
Ending balance, common stock, shares		9,035,294		9,035,294
Ending balance		$ 90		$ 90
Additional paid-in capital
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance				244,791
Stock option exercises, amount				(1,104)
Stock-based compensation				1,918
Net income				0
Other comprehensive loss				0
Ending balance		245,605		245,605
Retained earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance				148,141
Stock option exercises, amount
Stock-based compensation				0
Net income				39,362
Other comprehensive loss				0
Ending balance		187,572		187,572
Accumulated other comprehensive income
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance				1,386
Stock option exercises, amount				0
Stock-based compensation				0
Net income				0
Other comprehensive loss	[1]			919
Ending balance		$ 2,305		$ 2,305

[1] Other comprehensive income is comprised of unrealized gains and losses on available-for-sale investments. Unrealized gains before tax effect on available-for-sale securities were $1.5 million for the nine months ended December 30, 2017.