Business segment information - Schedule of Operating Segments Organized by Manufacturing Facilities and Include Three Reportable Segments (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Net sales:
Total net sales	$ 133,072	$ 140,973	$ 439,112	$ 431,091
Operating income (loss):
Defined benefit pension credit	1,346	4,750	5,143	14,250
Other postretirement benefit credit	1,403	1,299	4,557	3,898
Other	535	(508)	(2,317)	(2,702)
Total operating income	8,442	11,666	33,021	41,892
Non operating income (expense):
Interest expense	(274)	(319)	(967)	(922)
Other income (expense), net	(141)	113	(488)	661
Income before income taxes	8,027	11,460	31,566	41,631
Keystone Steel & Wire [Member]
Net sales:
Total net sales	122,268	133,328	420,409	418,347
Operating income (loss):
Total operating income	5,617	6,006	25,283	24,424
Engineered Wire Products, Inc. [Member]
Net sales:
Total net sales	18,929	16,492	48,653	44,902
Operating income (loss):
Total operating income	1,192	583	2,603	2,050
Keystone-Calumet, Inc. [Member]
Net sales:
Total net sales	6,359	7,132	21,948	23,044
Operating income (loss):
Total operating income	(1,651)	(464)	(2,248)	(28)
Elimination of Intersegment Sales [Member]
Net sales:
Total net sales	$ (14,484)	$ (15,979)	$ (51,898)	$ (55,202)