Segment Reporting and Geographic Information (Revenues by Segment) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue	$ 43,444us-gaap_SalesRevenueNet	$ 43,170us-gaap_SalesRevenueNet	$ 43,124us-gaap_SalesRevenueNet	$ 42,318us-gaap_SalesRevenueNet	$ 50,736us-gaap_SalesRevenueNet	$ 38,385us-gaap_SalesRevenueNet	$ 38,175us-gaap_SalesRevenueNet	$ 38,905us-gaap_SalesRevenueNet	$ 172,056us-gaap_SalesRevenueNet	$ 166,201us-gaap_SalesRevenueNet	$ 151,661us-gaap_SalesRevenueNet
Operating Segments [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue									172,223	166,347	160,148
Network Equipment segment [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue									86,705	90,711	87,727
Network Integration segment [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue									85,518	75,636	72,421
Intersegment adjustments [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue									$ (167)	$ (146)	$ (8,487)