Revenue Recognition (Details) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020 USD ($)	Sep. 30, 2020 USD ($)	Jun. 30, 2020 USD ($)	Mar. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2020 USD ($) unit	Dec. 31, 2019 USD ($) unit	Dec. 31, 2018 USD ($) unit
Disaggregation of Revenue [Line Items]
Net sales	$ 116,700	$ 134,772	$ 125,596	$ 137,483	$ 122,574	$ 113,500	$ 119,437	$ 113,822	$ 514,551	$ 469,333	$ 433,947
Total Units | unit									26,231,000	26,307,000	25,152,000
Rooftop Units
Disaggregation of Revenue [Line Items]
Net sales									$ 400,946	$ 349,427	$ 333,105
Total Units | unit									15,713,000	14,448,000	15,273,000
Condensing Units
Disaggregation of Revenue [Line Items]
Net sales									$ 21,149	$ 18,475	$ 18,282
Total Units | unit									1,920,000	1,738,000	2,007,000
Air Handlers
Disaggregation of Revenue [Line Items]
Net sales									$ 23,931	$ 24,265	$ 21,905
Total Units | unit									2,073,000	2,372,000	2,500,000
Outdoor Mechanical Rooms
Disaggregation of Revenue [Line Items]
Net sales									$ 2,842	$ 1,643	$ 2,408
Total Units | unit									33,000	33,000	38,000
Water-Source Heat Pumps
Disaggregation of Revenue [Line Items]
Net sales									$ 19,053	$ 25,447	$ 14,660
Total Units | unit									6,492,000	7,716,000	5,334,000
Part Sales
Disaggregation of Revenue [Line Items]
Net sales									$ 32,561	$ 33,331	$ 26,732
Other
Disaggregation of Revenue [Line Items]
Net sales									$ 14,069	$ 16,745	$ 16,855