Consolidated Statement of Earnings (USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Continuing Operations
Net sales	$ 1,939.3	$ 1,710.5	$ 1,489.3
Cost of products sold	1,287.3	1,197.9	1,043.3
Gross profit	652.0	512.6	446.0
Selling, general and administrative expenses	450.5	372.8	328.7
Flood related expense			35.4
Restructuring, impairment and settlement (income) expense - net	(3.9)	(11.2)	0.1
Contingent consideration adjustment	(3.3)
Interest Expense	9.2	9.3	6.9
Other (income) expense - net	(34.3)	(19.8)	0.5
Earnings before provision for income taxes	233.8	161.5	74.4
Provision for income taxes	71.2	50.3	17.3
Earnings from continuing operations	162.6	111.2	57.1
Discontinued Operations
Earnings from discontinued operations, less tax provision for income taxes of $15.5 in 2011 and $16.2 in 2010	(3.9)	43.0	54.4
(Loss)/gain on sale of discontinued EPC operations, less tax provision of $6.3 in 2012 and $145.6 in 2011	(3.9)	151.5
Net Earnings	158.7	305.7	111.5
Net loss attributable to noncontrolling interest:
Continuing operations			0.2
Net earnings attributable to A. O. Smith Corporation	$ 158.7	$ 305.7	$ 111.7
Net Earnings (Loss) Per Share of Common Stock
Continuing Operations	$ 3.52	$ 2.41	$ 1.25
Discontinued Operations	$ (0.08)	$ 4.22	$ 1.19
Net Earnings attributable to A. O. Smith Corporation	$ 3.44	$ 6.63	$ 2.44
Diluted Net Earnings (Loss) Per Share of Common Stock
Continuing Operations	$ 3.49	$ 2.39	$ 1.24
Discontinued Operations	$ (0.08)	$ 4.18	$ 1.18
Net Earnings attributable to A. O. Smith Corporation	$ 3.41	$ 6.57	$ 2.42