Multiemployer Pension Plans - (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Multiemployer Plans [Line Items]
Contributions	$ 16,109	$ 17,052
Heating, Piping and Refrigeration Pension Fund
Multiemployer Plans [Line Items]
Contributions	1,045	1,101
Plumbers Local No 98 Defined Benefit Pension Fund
Multiemployer Plans [Line Items]
Contributions	1,658	1,140
Plumbers and Pipefitters National Pension Fund
Multiemployer Plans [Line Items]
Contributions	947	1,040
Pipefitters Local 636 Defined Benefit Pension Fund
Multiemployer Plans [Line Items]
Contributions	1,206	1,369
Sheet Metal Workers' Pension Plan of Southern California, Arizona and Nevada
Multiemployer Plans [Line Items]
Contributions	1,322	1,908
Sheet Metal Workers’ National Pension Fund
Multiemployer Plans [Line Items]
Contributions	1,144	1,509
Sheet Metal Workers Local Union No. 80 Pension Fund
Multiemployer Plans [Line Items]
Contributions	1,383	1,033
Sheet Metal Workers Local 98 Pension Fund
Multiemployer Plans [Line Items]
Contributions	945	927
Steamfitters Local Union No. 420 Pension Fund
Multiemployer Plans [Line Items]
Contributions	591	825
Pipefitters Union Local No. 537 Pension Fund
Multiemployer Plans [Line Items]
Contributions	1,337	1,579
Plumbers & Pipefitters Local No 189 Pension Plan
Multiemployer Plans [Line Items]
Contributions	598	544
Plumbers & Pipefitters of Local Union No. 333 Pension Fund
Multiemployer Plans [Line Items]
Contributions	1,329	645
Southern California Pipe Trades Retirement Fund
Multiemployer Plans [Line Items]
Contributions	662	1,015
Electrical Workers Local No. 26 Pension Trust Fund
Multiemployer Plans [Line Items]
Contributions	348	341
Plumbers Union Local No. 12 Pension
Multiemployer Plans [Line Items]
Contributions	261	322
Sheet Metal Workers Local 7, Zone 1 Pension Plan
Multiemployer Plans [Line Items]
Contributions	383	350
Plumbers & Steamfitters Local 577 Pension Plan
Multiemployer Plans [Line Items]
Contributions	208	217
Laborers District Council Pension and Disability Trust Fund No. 2
Multiemployer Plans [Line Items]
Contributions	147	399
Laborers District Council Pension and Disability Trust Fund No. 2
Multiemployer Plans [Line Items]
Contributions	37	49
National Electrical Benefit Fund
Multiemployer Plans [Line Items]
Contributions	111	105
Airconditioning and Refrigeration Industry Retirement Trust Fund
Multiemployer Plans [Line Items]
Contributions	144	144
Plumbers and Steamfitters Local 486 Pension Fund
Multiemployer Plans [Line Items]
Contributions	40	44
Steamfitters Local #449 Pension Plan
Multiemployer Plans [Line Items]
Contributions	109	185
United Association Local Union No. 322 Pension Plan
Multiemployer Plans [Line Items]
Contributions	18	38
Sheet Metal Workers Local 224 Pension Fund
Multiemployer Plans [Line Items]
Contributions	20	17
Plumbers Local 27 Pension Fund
Multiemployer Plans [Line Items]
Contributions	18	56
All other plans
Multiemployer Plans [Line Items]
Contributions	$ 98	$ 150