Lines of Credit and Long-Term Debt - Lines of Credit (Details) - USD ($) $ in Thousands		3 Months Ended			12 Months Ended
	Jul. 01, 2016	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Apr. 29, 2015	Dec. 30, 2013
2013 Revolving Line
Lines of Credit
Maximum borrowing capacity									$ 7,000
Interest expense						$ 127	$ 383
Amortization of deferred financing costs to interest expense						46	$ 46
2015 Revolving Line
Lines of Credit
Maximum borrowing capacity	$ 25,000							$ 15,000
Number of months of monthly recurring revenue through June 30, 2017	4 months
Number of months of monthly recurring revenue thereafter	3 months
Minimum unrestricted cash and unused availability balance required	$ 3,000
Minimum EBITDA		$ 2,500	$ 2,250	$ 2,000
Minimum monthly recurring revenue retention rate (as a percent)	90.00%
Letter of credit liability		500			$ 500	500
Aggregate borrowings outstanding		0			0
Amounts available for borrowings		$ 24,500			$ 24,500
Interest rate (as a percent)		4.06%			4.06%
Interest expense					$ 570	290
Deferred financing costs		$ 141			141
Amortization of deferred financing costs to interest expense					$ 46	$ 35
2015 Revolving Line | Prime Rate
Lines of Credit
Spread on variable rate (as a percent)	0.50%
Floor rate (as a percent)	3.50%