Stock-based compensation plans (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended		1 Months Ended
	Apr. 04, 2015	Mar. 29, 2014	Apr. 04, 2015	Mar. 29, 2014	Dec. 31, 2014 Employee
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options outstanding (in shares)	0	0	0	0
Options exercisable (in shares)	0	0	0	0
Weighted Average Grant-Date Fair Value [Roll Forward]
Stock based compensation expense	$ 146	$ 68	$ 259	$ 127
Unrecognized compensation expense	1,071		1,071
Weighted average period for unrecognized compensation expense to be recognized			2 years 6 months
Restricted Stock [Member]
Number of shares of Restricted Stock [Roll Forward]
Non-vested balance, beginning of period (in shares)			168,600
Granted (in shares)			92,600
Vested (in shares)			(64,600)
Non-vested balance, end of period (in shares)	196,600		196,600
Weighted Average Grant-Date Fair Value [Roll Forward]
Non-vested balance, beginning of period (in dollars per share)			$ 5.27
Granted (in dollars per share)			$ 7.68
Vested (in dollars per share)			$ 6.32
Non-vested balance, ending of period (in dollars per share)	$ 6.07		$ 6.07
Restricted Stock [Member] | Eight Employees [Member]
Number of shares of Restricted Stock [Roll Forward]
Granted (in shares)					42,000
Weighted Average Grant-Date Fair Value [Roll Forward]
Number of employees directors with restricted stock grant					8
Estimated fair value of stock at date of grant					330
Period for recognition of unearned compensation					2 years
Charge to income for restricted stock					41
Quarterly charge to income for restricted stock					41
Restricted Stock [Member] | Three Employees [Member]
Number of shares of Restricted Stock [Roll Forward]
Granted (in shares)					20,000
Weighted Average Grant-Date Fair Value [Roll Forward]
Number of employees directors with restricted stock grant					3
Estimated fair value of stock at date of grant					139
Period for recognition of unearned compensation					5 years
Charge to income for restricted stock					7
Quarterly charge to income for restricted stock					7
Restricted Stock [Member] | Nine Non-Employees [Member]
Number of shares of Restricted Stock [Roll Forward]
Granted (in shares)			30,600
Weighted Average Grant-Date Fair Value [Roll Forward]
Number of employees directors with restricted stock grant			9
Estimated fair value of stock at date of grant			225
Period for recognition of unearned compensation			12 months
Charge to income for restricted stock			19
Quarterly charge to income for restricted stock			$ 56
1996 Equity Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares reserved and available for grant (in shares)	139,578	183,400	139,578	183,400
Options grants (in shares)	0	0	0	0
Options exercised (in shares)	0	0	0	0