Stockholders' Equity (Details) - USD ($)		3 Months Ended		6 Months Ended
		Sep. 26, 2015	Sep. 27, 2014	Sep. 26, 2015	Sep. 27, 2014
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance, common stock, shares				8,859,199
Beginning balance				$ 320,154,000
Stock option exercises, amount				1,093,000
Stock-based compensation				1,117,000
Net income		$ 8,070,000	$ 5,467,000	13,455,000	$ 11,226,000
Other comprehensive loss	[1]			$ (705,000)
Ending balance, common stock, shares		8,890,931		8,890,931
Ending balance		$ 335,114,000		$ 335,114,000
Pre-tax unrealized loss on available-for-sale investments				$ (1,100,000)
Common Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance, common stock, shares				8,859,199
Beginning balance				$ 89,000
Stock option exercises, shares				31,732
Stock option exercises, amount				$ 0
Stock-based compensation				0
Net income				0
Other comprehensive loss				$ 0
Ending balance, common stock, shares		8,890,931		8,890,931
Ending balance		$ 89,000		$ 89,000
Additional paid-in capital
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance				237,916,000
Stock option exercises, amount				1,093,000
Stock-based compensation				1,117,000
Net income				0
Other comprehensive loss				0
Ending balance		240,126,000		240,126,000
Retained earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance				81,645,000
Stock option exercises, amount				0
Stock-based compensation				0
Net income				13,455,000
Other comprehensive loss				0
Ending balance		95,100,000		95,100,000
Accumulated other comprehensive income
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance				504,000
Stock option exercises, amount				0
Stock-based compensation				0
Net income				0
Other comprehensive loss	[1]			(705,000)
Ending balance		$ (201,000)		$ (201,000)

[1] Other comprehensive income is comprised of unrealized gains and losses on available-for-sale investments. Unrealized losses before tax effect on available-for-sale securities were $1.1 million for the six months ended September 26, 2015.