Stockholders' Equity (Details) - USD ($)		3 Months Ended		6 Months Ended
		Oct. 01, 2016	Sep. 26, 2015	Oct. 01, 2016	Sep. 26, 2015
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance, common stock, shares				8,927,989
Beginning balance				$ 353,226,000
Stock option exercises, amount				781,000
Stock-based compensation				1,357,000
Net income		$ 9,341,000	$ 8,070,000	14,784,000	$ 13,455,000
Other comprehensive loss	[1]			$ 824,000
Ending balance, common stock, shares		8,990,813		8,990,813
Ending balance		$ 370,972,000		$ 370,972,000
Pre-tax unrealized loss on available-for-sale investments				$ 1,312,000
Common Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance, common stock, shares				8,927,989
Beginning balance				$ 89,000
Stock option exercises, shares				62,824
Stock option exercises, amount				$ 1,000
Stock-based compensation				0
Net income				0
Other comprehensive loss				$ 0
Ending balance, common stock, shares		8,990,813		8,990,813
Ending balance		$ 90,000		$ 90,000
Additional paid-in capital
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance				241,662,000
Stock option exercises, amount				780,000
Stock-based compensation				1,357,000
Net income				0
Other comprehensive loss				0
Ending balance		243,799,000		243,799,000
Retained earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance				110,186,000
Stock option exercises, amount				0
Stock-based compensation				0
Net income				14,784,000
Other comprehensive loss				0
Ending balance		124,970,000		124,970,000
Accumulated other comprehensive income
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance				1,289,000
Stock option exercises, amount				0
Stock-based compensation				0
Net income				0
Other comprehensive loss	[1]			824,000
Ending balance		$ 2,113,000		$ 2,113,000

[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 $1.3 million for the six months ended October 1, 2016.