Business Combinations Business Combinations - Purchase Price Allocation (Details) - USD ($) $ in Thousands			12 Months Ended
	Apr. 06, 2017	Aug. 04, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Jun. 30, 2017
Business Acquisition [Line Items]
Goodwill			$ 48,651	$ 43,052	$ 43,116
Cash paid			$ 8,894	$ 0	$ 0
Minimum
Business Acquisition [Line Items]
Intangible asset, estimated useful life			1 year
Maximum
Business Acquisition [Line Items]
Intangible asset, estimated useful life			15 years
Developed technology | Minimum
Business Acquisition [Line Items]
Intangible asset, estimated useful life			5 years
Developed technology | Maximum
Business Acquisition [Line Items]
Intangible asset, estimated useful life			15 years
Customer relationships | Minimum
Business Acquisition [Line Items]
Intangible asset, estimated useful life			10 years
Customer relationships | Maximum
Business Acquisition [Line Items]
Intangible asset, estimated useful life			15 years
Order backlog
Business Acquisition [Line Items]
Intangible asset, estimated useful life			1 year
Ecolink Intelligent Technology, Inc.
Business Acquisition [Line Items]
Cash and cash equivalents		$ 685
Accounts receivable		374
Inventories		1,412
Prepaid expenses and other current assets		253
Property, plant and equipment		16
Non-interest bearing liabilities		(1,557)
Net tangible assets acquired		1,183
Goodwill	$ 5,494	12,564
Total purchase price		24,527
Noncontrolling interest in Encore		(378)
Net purchase price		24,149
Less: Contingent consideration		(11,200)
Cash paid		12,949
Ecolink Intelligent Technology, Inc. | Minimum
Business Acquisition [Line Items]
Property, plant and equipment, estimated useful life			1 year
Ecolink Intelligent Technology, Inc. | Maximum
Business Acquisition [Line Items]
Property, plant and equipment, estimated useful life			4 years
Ecolink Intelligent Technology, Inc. | Trade name
Business Acquisition [Line Items]
Intangible assets		400				$ 400
Intangible asset, estimated useful life			7 years
Ecolink Intelligent Technology, Inc. | Developed technology
Business Acquisition [Line Items]
Intangible assets		9,080
Ecolink Intelligent Technology, Inc. | Developed technology | Minimum
Business Acquisition [Line Items]
Intangible asset, estimated useful life			4 years
Ecolink Intelligent Technology, Inc. | Developed technology | Maximum
Business Acquisition [Line Items]
Intangible asset, estimated useful life			14 years
Ecolink Intelligent Technology, Inc. | Customer relationships
Business Acquisition [Line Items]
Intangible assets		$ 1,300				5,000
Intangible asset, estimated useful life			5 years
Ecolink Intelligent Technology, Inc. | Order backlog
Business Acquisition [Line Items]
Intangible assets						$ 200
Residential Control Systems, Inc
Business Acquisition [Line Items]
Accounts receivable	429
Inventories	1,508
Prepaid expenses and other current assets	7
Property, plant and equipment	14
Current liabilities	(408)
Net tangible assets acquired	1,550
Goodwill			$ 5,500
Total purchase price	12,594
Less: Contingent consideration	(3,700)
Cash paid	8,894
Residential Control Systems, Inc | Minimum
Business Acquisition [Line Items]
Property, plant and equipment, estimated useful life			1 year
Residential Control Systems, Inc | Maximum
Business Acquisition [Line Items]
Property, plant and equipment, estimated useful life			4 years
Residential Control Systems, Inc | Trade name
Business Acquisition [Line Items]
Intangible assets	400
Intangible asset, estimated useful life			8 years
Residential Control Systems, Inc | Customer relationships
Business Acquisition [Line Items]
Intangible assets	5,000
Intangible asset, estimated useful life			10 years
Residential Control Systems, Inc | Order backlog
Business Acquisition [Line Items]
Intangible assets	$ 150
Intangible asset, estimated useful life			1 year