CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Cash and cash equivalents	$ 36,815	$ 43,772
Restricted cash and cash equivalents	11,301	13,169
Accounts receivable – trade, net	112,658	142,201
Accounts receivable – other	27,585	23,263
Contracts in progress	86,091	91,579
Inventories	61,390	63,103
Other current assets	25,292	27,044
Current assets held for sale	6,726	8,089
Total current assets	367,858	412,220
Net property, plant and equipment, and finance lease	90,577	97,053
Goodwill	47,020	47,160
Intangible assets	23,665	25,300
Right-of-use assets	11,367	12,498
Other assets	30,170	24,966
Non-current assets held for sale	7,296	7,322
Total assets	577,953	626,519
Revolving credit facilities	0	179,000
Last out term loans	0	103,953
Financing lease liabilities	820	(38)
Accounts payable	73,995	109,913
Accrued employee benefits	17,561	18,256
Advance billings on contracts	60,977	75,287
Accrued warranty expense	28,491	33,376
Operating lease liabilities	4,280	4,323
Other accrued liabilities	80,424	68,848
Current liabilities held for sale	7,537	9,538
Total current liabilities	274,085	602,494
Revolving credit facilities	164,700	0
Last out term loans	173,330	0
Pension and other accumulated postretirement benefit liabilities	243,829	259,272
Non-current finance lease liabilities	30,140	30,454
Non-current operating lease liabilities	7,374	8,388
Other non-current liabilities	23,149	20,850
Non-current liabilities held for sale	46	0
Total liabilities	916,653	921,458
Commitments and contingencies
Stockholders' deficit:
Common stock, par value $0.01 per share, authorized shares of 500,000; issued and outstanding shares of 49,312 and 46,374 at June 30, 2020 and December 31, 2019, respectively	4,732	4,699
Capital in excess of par value	1,150,999	1,142,614
Treasury stock at cost, 619 and 616 shares at June 30, 2020 and December 31, 2019, respectively	(105,717)	(105,707)
Accumulated deficit	(1,389,518)	(1,339,888)
Accumulated other comprehensive income	(281)	1,926
Stockholders' deficit attributable to shareholders	(339,785)	(296,356)
Non-controlling interest	1,085	1,417
Total stockholders' deficit	(338,700)	(294,939)
Total liabilities and stockholders' deficit	$ 577,953	$ 626,519