Summary of Significant Accounting Policies - Net Income Per Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 26, 2014	Jun. 27, 2014	Mar. 28, 2014	Dec. 31, 2013	Sep. 27, 2013	Jun. 28, 2013	Mar. 29, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Accounting Policies [Abstract]
Current Fiscal Year End Date									--12-31
Net Income	$ 1,225	$ 2,726	$ 3,233	$ 3,166	$ 3,704	$ 3,863	$ 4,055	$ 4,057	$ 10,350	$ 15,679	$ 16,165
Weighted average number of shares outstanding, basic (in shares)									15,120,000	15,365,000	15,172,000
Basic (in dollars per share)	$ 0.08	$ 0.18	$ 0.22	$ 0.21	$ 0.24	$ 0.25	$ 0.26	$ 0.26	$ 0.68	$ 1.02	$ 1.07
Number of shares, attribuatable to equity based compensation plans (in shares)									1,140,000	1,589,000	1,669,000
Dilutive effect on basic earnings per share (in dollars per share)									$ (0.04)	$ (0.10)	$ (0.11)
Weighted average number of shares outstanding, diluted (in shares)									16,260,000	16,954,000	16,841,000
Diluted (in dollars per share)	$ 0.08	$ 0.17	$ 0.20	$ 0.19	$ 0.22	$ 0.23	$ 0.24	$ 0.24	$ 0.64	$ 0.92	$ 0.96
Antidilutive securities not included in the computation of earnings per share	600,000				100,000				600,000	100,000	100,000