Business combinations, discontinued operations and related transactions - Summary of Operations of Disposed Furniture Components Business (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Business Combinations Discontinued Operations And Related Transactions [Line Items]
Gain on sale	$ 23.7
Total discontinued operations, net of tax	25.5	4.1	(0.5)
Compx Furniture Components [Member]
Business Combinations Discontinued Operations And Related Transactions [Line Items]
Net sales	60.7	59.0	59.1
Operating income	7.4	9.1	3.4
Income before taxes	7.2	9.1	3.5
Income tax expense	3.5	5.0	4.0
Income (loss) from discontinued operations, net of tax	3.7	4.1	(0.5)
Gain on sale	23.7
Income tax expense	1.9
Gain on sale discontinued operations, net of tax	21.8
Total discontinued operations, net of tax	25.5	4.1	(0.5)
Noncontrolling interest in income from discontinued operations	1.0	1.1	0.1
Noncontrolling interest in gain on sale of discontinued operations	6.1
Total noncontrolling interest in discontinued operations	7.1	1.1	0.1
Cash		6.3
Accounts receivables		6.1
Inventory		7.6
Other current assets		0.6
Goodwill		13.6
Property and equipment, net		17.4
Other noncurrent assets		0.3
Total assets		51.9
Current liabilities		7.9
Noncurrent liabilities		3.3
Total liabilities		11.2
Compx Furniture Components [Member] | Net of Noncontrolling Interest [Member]
Business Combinations Discontinued Operations And Related Transactions [Line Items]
Total discontinued operations, net of tax	$ 18.4	$ 3.0	$ (0.4)