Contingencies Details (Details)	6 Months Ended
	Jun. 30, 2018
Loss contingency number of claims alleged	3
Former Davey employee defendants [Member]
Loss contingency, number of defendants	1
Wolf employee defendants [Member]
Loss contingency, number of defendants	2
Former Wolf employee defendants [Member]
Loss contingency, number of defendants	1
Defendants for which Davey has retained separate counsel [Member]
Loss contingency, number of defendants	3