Subsidiary Guarantors (Condensed Consolidating Balance Sheet) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
CURRENT ASSETS:
Cash and cash equivalents	$ 15,852	$ 11,167	$ 14,184	$ 42,389
Accounts receivable—net	75,533	88,091
Contract revenues in excess of billings	90,788	95,012
Inventories	34,600	37,137
Prepaid expenses	5,183	12,407
Other current assets	40,228	63,412
Total current assets	262,184	307,226
PROPERTY AND EQUIPMENT—Net	407,294	413,008	430,210
GOODWILL	83,576	83,576	83,576	86,326
OTHER INTANGIBLE ASSETS — Net	908	1,499
INVENTORIES—Noncurrent	54,023	52,602
INVESTMENTS IN JOINT VENTURES	2,714	4,734	3,761
ASSETS HELD FOR SALE— Noncurrent	8,530	9,299
OTHER	13,128	21,644
TOTAL	832,357	893,588	898,124
LIABILITIES AND EQUITY
Accounts payable	87,659	103,185
Accrued expenses	56,218	69,043
Billings in excess of contract revenues	3,615	5,141
Current portion of long-term debt	2,758	2,465
Total current liabilities	150,250	179,834
LONG-TERM DEBT	333,141	286,291
REVOLVING CREDIT FACILITY	95,000	104,111
DEFERRED INCOME TAXES	25,561	68,449
OTHER	7,109	7,013
Total liabilities	611,061	645,698
TOTAL EQUITY	221,296	247,890	252,173	255,963
TOTAL	832,357	893,588
Reportable Legal Entities [Member] | Guarantor Subsidiaries [Member]
CURRENT ASSETS:
Cash and cash equivalents	15,794	10,414	11,698	44,636
Accounts receivable—net	75,431	75,412
Contract revenues in excess of billings	90,788	91,478
Inventories	34,600	37,137
Prepaid expenses	5,183	12,287
Other current assets	38,731	60,844
Total current assets	260,527	287,572
PROPERTY AND EQUIPMENT—Net	407,293	407,516
GOODWILL	83,576	83,576
OTHER INTANGIBLE ASSETS — Net	571	1,067
INVENTORIES—Noncurrent	54,023	52,602
INVESTMENTS IN JOINT VENTURES	2,555	4,685
ASSETS HELD FOR SALE— Noncurrent	8,530	8,390
RECEIVABLES FROM AFFILIATES	45,375	58,284
OTHER	7,971	14,692
TOTAL	870,421	918,384
LIABILITIES AND EQUITY
Accounts payable	87,379	101,795
Accrued expenses	50,382	55,940
Billings in excess of contract revenues	3,615	4,699
Current portion of long-term debt	1,546	305
Total current liabilities	142,922	162,739
DEFERRED INCOME TAXES		(1,833)
PAYABLES TO AFFILIATES	161,979	80,769
INVESTMENTS IN SUBSIDIARIES	41,358	32,000
OTHER	6,940	5,925
Total liabilities	353,199	279,600
TOTAL EQUITY	517,222	638,784
TOTAL	870,421	918,384
Reportable Legal Entities [Member] | Non Guarantor Subsidiaries [Member]
CURRENT ASSETS:
Cash and cash equivalents	38	751	2,484	(2,249)
Accounts receivable—net	102	14,242
Contract revenues in excess of billings		3,534
Prepaid expenses		120
Other current assets	1,497	2,568
Total current assets	1,637	21,215
PROPERTY AND EQUIPMENT—Net	1	5,492
OTHER INTANGIBLE ASSETS — Net	337	432
INVESTMENTS IN JOINT VENTURES	159	49
ASSETS HELD FOR SALE— Noncurrent		909
RECEIVABLES FROM AFFILIATES	6,754	16,807
OTHER	1	1
TOTAL	8,889	44,905
LIABILITIES AND EQUITY
Accounts payable	280	2,879
Accrued expenses	1,312	3,222
Billings in excess of contract revenues		499
Current portion of long-term debt		1,015
Total current liabilities	1,592	7,615
PAYABLES TO AFFILIATES	54,442	70,921
OTHER		937
Total liabilities	56,034	79,473
TOTAL EQUITY	(47,145)	(34,568)
TOTAL	8,889	44,905
Reportable Legal Entities [Member] | GLDD Corporation [Member]
CURRENT ASSETS:
Cash and cash equivalents	20	2	$ 2	$ 2
Total current assets	20	2
RECEIVABLES FROM AFFILIATES	170,323	82,340
INVESTMENTS IN SUBSIDIARIES	511,435	636,216
OTHER	5,156	6,951
TOTAL	686,934	725,509
LIABILITIES AND EQUITY
Accounts payable		17
Accrued expenses	4,524	9,881
Current portion of long-term debt	1,212	1,145
Total current liabilities	5,736	11,043
LONG-TERM DEBT	333,141	286,291
REVOLVING CREDIT FACILITY	95,000	104,111
DEFERRED INCOME TAXES	25,561	70,282
PAYABLES TO AFFILIATES	6,031	5,741
OTHER	169	151
Total liabilities	465,638	477,619
TOTAL EQUITY	221,296	247,890
TOTAL	686,934	725,509
Consolidation Eliminations [Member]
CURRENT ASSETS:
Accounts receivable—net		(1,563)
Total current assets		(1,563)
RECEIVABLES FROM AFFILIATES	(222,452)	(157,431)
INVESTMENTS IN SUBSIDIARIES	(511,435)	(636,216)
TOTAL	(733,887)	(795,210)
LIABILITIES AND EQUITY
Accounts payable		(1,506)
Billings in excess of contract revenues		(57)
Total current liabilities		(1,563)
PAYABLES TO AFFILIATES	(222,452)	(157,431)
INVESTMENTS IN SUBSIDIARIES	(41,358)	(32,000)
Total liabilities	(263,810)	(190,994)
TOTAL EQUITY	(470,077)	(604,216)
TOTAL	$ (733,887)	$ (795,210)