Identifiable Intangible Assets - (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	$ 79,448		$ 79,448
Finite-Lived Intangible Assets, Accumulated Amortization	69,680		69,175
Intangible Assets, Net (Excluding Goodwill)	9,768		10,273
Amortization of Intangible Assets	505	$ 595
Future Amortization Expense, Remainder of Fiscal Year	1,428
Future Amortization Expense, Year One	1,496
Future Amortization Expense, Year Two	1,496
Future Amortization Expense, Year Three	1,294
Future Amortization Expense, Year Four	546
Future Amortization Expense, Year Five	480
Developed Technology Rights [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	65,527		65,527
Finite-Lived Intangible Assets, Accumulated Amortization	57,388		56,986
Intangible Assets, Net (Excluding Goodwill)	8,139		8,541
Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	9,560		9,560
Finite-Lived Intangible Assets, Accumulated Amortization	8,592		8,514
Intangible Assets, Net (Excluding Goodwill)	968		1,046
Trade Names [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	4,361		4,361
Finite-Lived Intangible Assets, Accumulated Amortization	3,700		3,675
Intangible Assets, Net (Excluding Goodwill)	$ 661		$ 686