Revenue Recognition - Disaggregated Revenue (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Disaggregation Of Revenue [Line Items]
Disaggregated revenue	$ 14,641	$ 16,694	$ 43,917	$ 56,575
Partner Solutions [Member]
Disaggregation Of Revenue [Line Items]
Disaggregated revenue	12,556	14,241	37,341	47,297
Edge to Cloud [Member]
Disaggregation Of Revenue [Line Items]
Disaggregated revenue	2,085	2,453	6,576	9,278
North America [Member]
Disaggregation Of Revenue [Line Items]
Disaggregated revenue	12,714	15,441	39,281	52,909
North America [Member] | Partner Solutions [Member]
Disaggregation Of Revenue [Line Items]
Disaggregated revenue	10,851	13,715	33,363	45,115
North America [Member] | Edge to Cloud [Member]
Disaggregation Of Revenue [Line Items]
Disaggregated revenue	1,863	1,726	5,918	7,794
Europe [Member]
Disaggregation Of Revenue [Line Items]
Disaggregated revenue	341	674	1,500	2,502
Europe [Member] | Partner Solutions [Member]
Disaggregation Of Revenue [Line Items]
Disaggregated revenue	164	526	1,004	1,821
Europe [Member] | Edge to Cloud [Member]
Disaggregation Of Revenue [Line Items]
Disaggregated revenue	177	148	496	681
Asia [Member]
Disaggregation Of Revenue [Line Items]
Disaggregated revenue	1,586	579	3,136	1,164
Asia [Member] | Partner Solutions [Member]
Disaggregation Of Revenue [Line Items]
Disaggregated revenue	1,541		2,974	361
Asia [Member] | Edge to Cloud [Member]
Disaggregation Of Revenue [Line Items]
Disaggregated revenue	$ 45	$ 579	$ 162	$ 803