Revenue Recognition (Disaggregated Net Sales) (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019 USD ($) unit	Jun. 30, 2018 USD ($) unit	Jun. 30, 2019 USD ($) unit	Jun. 30, 2018 USD ($) unit
Disaggregation of Revenue [Line Items]
Net Sales	$ 119,437	$ 109,588	$ 233,259	$ 208,670
Rooftop Units
Disaggregation of Revenue [Line Items]
Net Sales	$ 88,757	$ 83,665	$ 177,100	$ 158,480
Total Units | unit	3,797,000	4,175,000	7,559,000	7,643,000
Condensing Units
Disaggregation of Revenue [Line Items]
Net Sales	$ 5,156	$ 4,855	$ 9,206	$ 9,136
Total Units | unit	479,000	625,000	873,000	1,036,000
Air Handlers
Disaggregation of Revenue [Line Items]
Net Sales	$ 6,033	$ 6,553	$ 11,627	$ 11,793
Total Units | unit	537,000	818,000	1,117,000	1,354,000
Outdoor Mechanical Rooms
Disaggregation of Revenue [Line Items]
Net Sales	$ 825	$ 894	$ 1,307	$ 1,867
Total Units | unit	10,000	13,000	21,000	27,000
Water Source Heat Pumps
Disaggregation of Revenue [Line Items]
Net Sales	$ 6,822	$ 2,741	$ 12,666	$ 7,128
Total Units | unit	2,377,000	1,004,000	4,666,000	2,618,000
Part Sales
Disaggregation of Revenue [Line Items]
Net Sales	$ 8,799	$ 6,702	$ 15,289	$ 12,662
Other
Disaggregation of Revenue [Line Items]
Net Sales	$ 3,045	$ 4,178	$ 6,064	$ 7,604
Total Units | unit	7,200,000	6,635,000	14,236,000	12,678,000