Uncompleted Contracts - Gross and Net Amounts of Uncompleted Contracts (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Jun. 30, 2017
Disclosure Customer Contracts Additional Information [Abstract]
Costs incurred and estimated earnings recognized on uncompleted contracts	$ 1,451,623	$ 1,919,054
Billings on uncompleted contracts	1,451,229	1,903,001
Total	394	16,053
Shown on balance sheet as:
Costs and estimated earnings in excess of billings on uncompleted contracts	65,953	91,180
Billings on uncompleted contracts in excess of costs and estimated earnings	65,559	75,127
Total	$ 394	$ 16,053