Acquisitions -Recognized Identified Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 18, 2019	Sep. 30, 2019	Dec. 31, 2018
Acquired Finite-Lived Intangible Assets [Line Items]
Tangible assets			$ 1,344
Goodwill	$ 41,214	$ 41,386	30,163		$ 11,051
Property, plant and equipment – net			712
Total assets			55,929
Accounts payable and accrued expenses			629
Warranty liability			1,412
Deferred revenue			715
Earn-Out liability			3,340
Consideration paid			49,833
Developed technology
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets			17,600
Customer relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets			4,700
Trade name
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets			900
Trademark
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets			510
Drive-Thru Communications Systems, 3M
Acquired Finite-Lived Intangible Assets [Line Items]
Tangible assets			0
Goodwill			2,390	$ 2,400
Property, plant and equipment – net			712
Total assets			8,412	8,400
Accounts payable and accrued expenses			0
Warranty liability			1,412
Deferred revenue			0
Earn-Out liability			0
Consideration paid			7,000
Drive-Thru Communications Systems, 3M | Developed technology
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets			1,200	1,200
Drive-Thru Communications Systems, 3M | Customer relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets			3,600	$ 3,600
Drive-Thru Communications Systems, 3M | Trade name
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets			0
Drive-Thru Communications Systems, 3M | Trademark
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets			510
Accsys llc (restaurant magic)
Acquired Finite-Lived Intangible Assets [Line Items]
Tangible assets			1,344
Goodwill			27,773
Property, plant and equipment – net			0
Total assets			47,517
Accounts payable and accrued expenses			629
Warranty liability			0
Deferred revenue			715
Earn-Out liability			3,340
Consideration paid			42,833
Accsys llc (restaurant magic) | Developed technology
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets			16,400
Accsys llc (restaurant magic) | Customer relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets			1,100
Accsys llc (restaurant magic) | Trade name
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets			900
Accsys llc (restaurant magic) | Trademark
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets			$ 0