Commitments and Contingencies (Details Textual) $ in Millions	Sep. 30, 2017 USD ($)
Other Commitments [Line Items]
Outstanding Performance Bonds	$ 410.9
Estimated Cost to Complete Bonded Projects	21.8
Purchase Commitment, Remaining Minimum Amount Committed	10.2
Maximum [Member]
Other Commitments [Line Items]
Loss Contingency Insurance Policy Deductible for Each Line of Coverage Excluding Health	1.0
Loss Contingency Health Insurance Deductible For Qualified Individuals	$ 0.2