Multiemployer Pension Plans - (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Multiemployer Plans [Line Items]
Contributions	$ 17,052	$ 16,439
Heating, Piping and Refrigeration Pension Fund
Multiemployer Plans [Line Items]
Contributions	1,101	1,763
Plumbers Local No 98 Defined Benefit Pension Fund
Multiemployer Plans [Line Items]
Contributions	1,140	1,480
Plumbers and Pipefitters National Pension Fund
Multiemployer Plans [Line Items]
Contributions	1,040	1,443
Pipefitters Local 636 Defined Benefit Pension Fund
Multiemployer Plans [Line Items]
Contributions	1,369	1,393
Sheet Metal Workers' Pension Plan of Southern California, Arizona and Nevada
Multiemployer Plans [Line Items]
Contributions	1,908	1,392
Sheet Metal Workers’ National Pension Fund
Multiemployer Plans [Line Items]
Contributions	1,509	1,283
Sheet Metal Workers Local Union No. 80 Pension Fund
Multiemployer Plans [Line Items]
Contributions	1,033	1,217
Sheet Metal Workers Local 98 Pension Fund
Multiemployer Plans [Line Items]
Contributions	927	1,133
Steamfitters Local Union No. 420 Pension Fund
Multiemployer Plans [Line Items]
Contributions	825	902
Pipefitters Union Local No. 537 Pension Fund
Multiemployer Plans [Line Items]
Contributions	1,579	805
Plumbers & Pipefitters Local No 189 Pension Plan
Multiemployer Plans [Line Items]
Contributions	544	637
Plumbers & Pipefitters of Local Union No. 333 Pension Fund
Multiemployer Plans [Line Items]
Contributions	645	535
Southern California Pipe Trades Retirement Fund
Multiemployer Plans [Line Items]
Contributions	1,015	529
Electrical Workers Local No. 26 Pension Trust Fund
Multiemployer Plans [Line Items]
Contributions	341	404
Plumbers Union Local No. 12 Pension
Multiemployer Plans [Line Items]
Contributions	322	277
Sheet Metal Workers Local 7, Zone 1 Pension Plan
Multiemployer Plans [Line Items]
Contributions	350	235
Plumbers & Steamfitters Local 577 Pension Plan
Multiemployer Plans [Line Items]
Contributions	217	194
Laborers District Council Pension and Disability Trust Fund No. 2
Multiemployer Plans [Line Items]
Contributions	399	163
Laborers District Council Pension and Disability Trust Fund No. 2
Multiemployer Plans [Line Items]
Contributions	49	119
National Electrical Benefit Fund
Multiemployer Plans [Line Items]
Contributions	105	110
Airconditioning and Refrigeration Industry Retirement Trust Fund
Multiemployer Plans [Line Items]
Contributions	144	93
Plumbers and Steamfitters Local 486 Pension Fund
Multiemployer Plans [Line Items]
Contributions	44	93
Steamfitters Local 449 Pension Plan
Multiemployer Plans [Line Items]
Contributions	185	38
United Association Local Union No. 322 Pension Plan
Multiemployer Plans [Line Items]
Contributions	38	26
Sheet Metal Workers Local 224 Pension Fund
Multiemployer Plans [Line Items]
Contributions	17	19
Plumbers Local 27 Pension Fund
Multiemployer Plans [Line Items]
Contributions	56	18
All other plans
Multiemployer Plans [Line Items]
Contributions	$ 150	$ 138