Revenue Recognition - Disaggregated Net Sales (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021 USD ($) unit	Sep. 30, 2020 USD ($) unit	Sep. 30, 2021 USD ($) unit	Sep. 30, 2020 USD ($) unit
Disaggregation of Revenue [Line Items]
Net Sales	$ 138,571	$ 134,772	$ 398,235	$ 397,851
Total Units | unit	6,530,000	7,352,000	20,034,000	20,302,000
Rooftop units
Disaggregation of Revenue [Line Items]
Net Sales	$ 103,900	$ 102,750	$ 298,695	$ 312,725
Total Units | unit	3,746,000	4,372,000	11,362,000	12,179,000
Condensing units
Disaggregation of Revenue [Line Items]
Net Sales	$ 6,797	$ 6,304	$ 20,630	$ 15,307
Total Units | unit	560,000	593,000	1,696,000	1,447,000
Air handlers
Disaggregation of Revenue [Line Items]
Net Sales	$ 6,279	$ 5,805	$ 19,958	$ 18,068
Total Units | unit	646,000	534,000	1,846,000	1,545,000
Outdoor mechanical rooms
Disaggregation of Revenue [Line Items]
Net Sales	$ 208	$ 867	$ 1,183	$ 2,216
Total Units | unit	2,000	6,000	22,000	22,000
Water source heat pumps
Disaggregation of Revenue [Line Items]
Net Sales	$ 5,215	$ 6,770	$ 16,305	$ 14,269
Total Units | unit	1,576,000	1,847,000	5,108,000	5,109,000
Part sales
Disaggregation of Revenue [Line Items]
Net Sales	$ 12,102	$ 10,484	$ 30,325	$ 24,562
Other
Disaggregation of Revenue [Line Items]
Net Sales	$ 4,070	$ 1,792	$ 11,139	$ 10,704