Investments (Unrealized Losses and Fair Value by Length of Time) (Details) - USD ($) $ in Thousands	Dec. 26, 2020	Mar. 28, 2020
Debt Securities in a Continuous Unrealized Loss Position
Less than 12 Months, Fair Value	$ 1,468	$ 4,481
Less than 12 month, Unrealized Losses	(12)	(67)
12 Months or Longer, Fair Value	460	1,880
12 Months or Longer, Unrealized Losses	(8)	(27)
Debt Securities, Available-for-sale, Unrealized Loss Position	1,928	6,361
Gross Unrealized Losses	(20)	(94)
Residential mortgage-backed securities
Debt Securities in a Continuous Unrealized Loss Position
Less than 12 Months, Fair Value	342	133
Less than 12 month, Unrealized Losses	(9)	0
12 Months or Longer, Fair Value	460	1,779
12 Months or Longer, Unrealized Losses	(8)	(26)
Debt Securities, Available-for-sale, Unrealized Loss Position	802	1,912
Gross Unrealized Losses	(17)	(26)
State and political subdivision debt securities
Debt Securities in a Continuous Unrealized Loss Position
Less than 12 Months, Fair Value	321	601
Less than 12 month, Unrealized Losses	(1)	(2)
12 Months or Longer, Fair Value	0	101
12 Months or Longer, Unrealized Losses	0	(1)
Debt Securities, Available-for-sale, Unrealized Loss Position	321	702
Gross Unrealized Losses	(1)	(3)
Corporate Debt Securities
Debt Securities in a Continuous Unrealized Loss Position
Less than 12 Months, Fair Value	805	3,747
Less than 12 month, Unrealized Losses	(2)	(65)
12 Months or Longer, Fair Value	0	0
12 Months or Longer, Unrealized Losses	0	0
Debt Securities, Available-for-sale, Unrealized Loss Position	805	3,747
Gross Unrealized Losses	$ (2)	$ (65)