Acquisitions - Consideration Paid and Estimated Fair Value of Assets Acquired (Details) - USD ($) $ in Thousands			12 Months Ended
	Mar. 13, 2015	Dec. 08, 2014	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Calculation of Consideration:
Cash not yet paid			$ 0	$ 417	$ 434
Estimated Tangible and Intangible Net Assets:
Goodwill			24,723	24,723	$ 21,374
SecurityTrax
Calculation of Consideration:
Cash paid, net of working capital adjustment	$ 5,612		200	200
Cash not yet paid	400
Total consideration	6,712
Estimated Tangible and Intangible Net Assets:
Current assets	14
Current liabilities	(7)
Goodwill	3,328
Total estimated tangible and intangible net assets	6,712
SecurityTrax | Customer Relationships
Estimated Tangible and Intangible Net Assets:
Intangible assets	1,699
SecurityTrax | Developed Technology
Estimated Tangible and Intangible Net Assets:
Intangible assets	1,407
SecurityTrax | Trade Name
Estimated Tangible and Intangible Net Assets:
Intangible assets	271
SecurityTrax | Contingent Consideration, Earn Out Program
Calculation of Consideration:
Contingent consideration liability	$ 700
Secure-i
Calculation of Consideration:
Cash paid, net of working capital adjustment		$ 2,610	$ 145	$ 145
Cash not yet paid		290
Total consideration		2,900
Estimated Tangible and Intangible Net Assets:
Current assets		16
Other long-term assets		43
Intangible assets		700
Liabilities		(59)
Goodwill		2,202
Total estimated tangible and intangible net assets		2,900
Secure-i | Customer Relationships
Estimated Tangible and Intangible Net Assets:
Intangible assets		208
Secure-i | Developed Technology
Estimated Tangible and Intangible Net Assets:
Intangible assets		228
Secure-i | Other intangibles
Estimated Tangible and Intangible Net Assets:
Intangible assets		$ 262