Acquisitions (Narrative) (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016	Mar. 31, 2016
Business Acquisition [Line Items]
Goodwill	$ 15,794	$ 15,794	$ 8,994
Contingent consideration fair value	2,200
Challenger And Hybrid [Member]
Business Acquisition [Line Items]
Acquisition purchase price		22,800
Contingent consideration liability	2,200	6,000
Cash		1,200
Intangible assets		9,900
Net liabilities assumed		1,200
Goodwill		$ 12,900
Challenger And Hybrid [Member] | Other Long-Term Liabilities [Member]
Business Acquisition [Line Items]
Contingent consideration liability	1,700
Challenger And Hybrid [Member] | Accrued Expenses And Other Current Liabilities [Member]
Business Acquisition [Line Items]
Contingent consideration liability	$ 500