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Revenue Recognition (Details) - USD ($) $ in Thousands	12 Months Ended
Revenue Recognition (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Disaggregation of revenue [Line Items]
Revenue from contracts with customers	$ 1,024,791
Contract with customer, asset and liability [Abstract]
Revenue recognized	1,443
Contract liabilities - current	2,907	$ 2,072
Contract liabilities - noncurrent	2,287	2,020
Net contract liabilities	5,194	$ 4,092
Utility
Disaggregation of revenue [Line Items]
Revenue from contracts with customers	537,484
Residential and Commercial
Disaggregation of revenue [Line Items]
Revenue from contracts with customers	486,005
All Other
Disaggregation of revenue [Line Items]
Revenue from contracts with customers	1,302
United States
Disaggregation of revenue [Line Items]
Revenue from contracts with customers	949,317
United States \| Utility
Disaggregation of revenue [Line Items]
Revenue from contracts with customers	499,242
United States \| Residential and Commercial
Disaggregation of revenue [Line Items]
Revenue from contracts with customers	448,773
United States \| All Other
Disaggregation of revenue [Line Items]
Revenue from contracts with customers	1,302
Canada
Disaggregation of revenue [Line Items]
Revenue from contracts with customers	75,474
Canada \| Utility
Disaggregation of revenue [Line Items]
Revenue from contracts with customers	38,242
Canada \| Residential and Commercial
Disaggregation of revenue [Line Items]
Revenue from contracts with customers	37,232
Canada \| All Other
Disaggregation of revenue [Line Items]
Revenue from contracts with customers	0
Tree and plant care
Disaggregation of revenue [Line Items]
Revenue from contracts with customers	683,901
Tree and plant care \| Utility
Disaggregation of revenue [Line Items]
Revenue from contracts with customers	394,481
Tree and plant care \| Residential and Commercial
Disaggregation of revenue [Line Items]
Revenue from contracts with customers	290,940
Tree and plant care \| All Other
Disaggregation of revenue [Line Items]
Revenue from contracts with customers	(1,520)
Grounds maintenance
Disaggregation of revenue [Line Items]
Revenue from contracts with customers	117,498
Grounds maintenance \| Utility
Disaggregation of revenue [Line Items]
Revenue from contracts with customers	0
Grounds maintenance \| Residential and Commercial
Disaggregation of revenue [Line Items]
Revenue from contracts with customers	117,498
Grounds maintenance \| All Other
Disaggregation of revenue [Line Items]
Revenue from contracts with customers	0
Storm damage services
Disaggregation of revenue [Line Items]
Revenue from contracts with customers	23,311
Storm damage services \| Utility
Disaggregation of revenue [Line Items]
Revenue from contracts with customers	13,864
Storm damage services \| Residential and Commercial
Disaggregation of revenue [Line Items]
Revenue from contracts with customers	9,447
Storm damage services \| All Other
Disaggregation of revenue [Line Items]
Revenue from contracts with customers	0
Consulting and other
Disaggregation of revenue [Line Items]
Revenue from contracts with customers	200,081
Consulting and other \| Utility
Disaggregation of revenue [Line Items]
Revenue from contracts with customers	129,139
Consulting and other \| Residential and Commercial
Disaggregation of revenue [Line Items]
Revenue from contracts with customers	68,120
Consulting and other \| All Other
Disaggregation of revenue [Line Items]
Revenue from contracts with customers	$ 2,822