Investments (Details Textual) - USD ($)	3 Months Ended		6 Months Ended
	Sep. 30, 2017	Oct. 01, 2016	Sep. 30, 2017	Oct. 01, 2016	Apr. 01, 2017
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	$ 3,522,000		$ 3,522,000		$ 2,582,000
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	(318,000)		(318,000)		(361,000)
Investments (Textual) [Abstract]
Value of investments to be other-than-temporarily impaired			0
Gross gains realized	570,000	$ 208,000	735,000	$ 661,000
Gross losses realized	(61,000)	$ (108,000)	(122,000)	$ (257,000)
US Treasury and Government [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	0		0		0
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	$ (2,000)		$ (2,000)		$ (1,000)