Segment Information and Major Customers - Sales Information by Product Category (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Revenue from External Customer [Line Items]
Sales	$ 159,094	$ 177,404	$ 162,233	$ 143,013	$ 139,756	$ 162,125	$ 183,998	$ 134,735	$ 641,744	$ 620,614	$ 717,229
Carrier Systems [Member]
Revenue from External Customer [Line Items]
Sales									427,850	399,646	420,289
Business Networking [Member]
Revenue from External Customer [Line Items]
Sales									168,871	149,304	162,186
Loop Access [Member]
Revenue from External Customer [Line Items]
Sales									$ 45,023	$ 71,664	$ 134,754