Percentage-of-completion method (Details 8) - USD ($) $ in Thousands		Dec. 31, 2016	Dec. 31, 2015
Accounting Policies [Abstract]
Costs and estimated earnings in excess of billings on uncompleted contracts		$ 64,558	$ 64,369
Billings in excess of costs and estimated earnings on uncompleted contracts		64,832	68,048
Short-term retainage	[1]	45,109	46,207
Long-term retainage	[2]	1,506	1,605
Total retainage		$ 46,615	$ 47,812

[1] Expected to be paid within one year or less and included in receivables, net.

[2] Included in deferred charges and other assets - other.