New Accounting Pronouncements - Schedule of New Accounting Standards Adoption Impacts Balance Sheets (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Dec. 30, 2017
ASSETS
Inventory delivered systems	$ 1,493		$ 1,534
LIABILITIES AND STOCKHOLDERS’ EQUITY
Deferred Revenue (Current)	9,029		7,408
Retained earnings	$ 26,136		$ 9,113
Topic 606 Adoption [Member]
ASSETS
Inventory delivered systems		$ 808
LIABILITIES AND STOCKHOLDERS’ EQUITY
Deferred Revenue (Current)		5,742
Retained earnings		10,053
Adjustments Due to Adoption of ASC 606 [Member] | Topic 606 Adoption [Member]
ASSETS
Inventory delivered systems		(726)
LIABILITIES AND STOCKHOLDERS’ EQUITY
Deferred Revenue (Current)		(1,666)
Retained earnings		$ 940