Business Combinations - Additional Disclosures (Details) - USD ($) $ in Thousands				12 Months Ended
	Apr. 06, 2017	Apr. 21, 2016	Aug. 04, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Business Acquisition [Line Items]
Cash consideration				$ 8,894	$ 0	$ 0
Long-term contingent consideration				13,400	10,500
Ecolink Intelligent Technology, Inc.
Business Acquisition [Line Items]
Purchase price			$ 24,100
Cash consideration			12,949
Contingent consideration			11,200
Acquisition costs			200
Fair value of noncontrolling interest			$ 378
Net sales since acquisition date				33,000	4,800	1,300
Net loss since acquisition date				700	1,600	1,000
Period of recognition for earnout payments to acquiree (in years)			5 years
Long-term contingent consideration				14,900	10,500	$ 11,800
Increase (decrease) in earnout contingent consideration				4,400	(1,300)
Ecolink Intelligent Technology, Inc. | Other Nonoperating Income (Expense)
Business Acquisition [Line Items]
Deconsolidation gain		$ 65
Ecolink Intelligent Technology, Inc. | Income Approach Valuation Technique
Business Acquisition [Line Items]
Fair value inputs, discount rate			15.50%
Ecolink Intelligent Technology, Inc. | Encore Controls LLC | Variable Interest Entity, Primary Beneficiary
Business Acquisition [Line Items]
Acquired ownership interest of Acquiree's subsidiary (percentage)			50.00%
Aggregated fair value of net assets acquired			$ 700
Fair value of noncontrolling interest			$ 400
Residential Control Systems, Inc
Business Acquisition [Line Items]
Purchase price	$ 12,600
Cash consideration	8,894
Contingent consideration	3,700
Acquisition costs	200			100
Net sales since acquisition date				3,500
Net loss since acquisition date				400
Additional earnout payments	10,000
Contingent consideration	$ 3,700
Pro forma information, increase (decrease) in amortization expense, net				100	$ 700
Residential Control Systems, Inc | Income Approach Valuation Technique
Business Acquisition [Line Items]
Fair value inputs, discount rate	24.80%
Other Accrued Liabilities | Ecolink Intelligent Technology, Inc.
Business Acquisition [Line Items]
Long-term contingent consideration				3,800
Long-term Contingent Consideration | Ecolink Intelligent Technology, Inc.
Business Acquisition [Line Items]
Long-term contingent consideration				11,100
Long-term Contingent Consideration | Residential Control Systems, Inc
Business Acquisition [Line Items]
Long-term contingent consideration				$ 2,300