Commitments and Contingencies - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	9 Months Ended	12 Months Ended		12 Months Ended					3 Months Ended			3 Months Ended			3 Months Ended			9 Months Ended	3 Months Ended	9 Months Ended
	Sep. 30, 2012 claim LegalMatter	Dec. 31, 2011 claim LegalMatter	Mar. 31, 2012	Dec. 31, 2010 Minimum LegalMatter	Dec. 31, 2010 Maximum LegalMatter	Sep. 30, 2012 Claims that Specify Amount of Damages Sought LegalMatter	Sep. 30, 2012 Claims that Cite Jurisdictional Amounts LegalMatter	Sep. 30, 2012 Claims that Specify Amount of Damages Sought not Based on Jurisdictional Requirements LegalMatter	Sep. 30, 2012 Claims that Specify Amount of Damages Sought not Based on Jurisdictional Requirements Minimum LegalMatter	Sep. 30, 2012 Claims that Specify Amount of Damages Sought not Based on Jurisdictional Requirements Maximum LegalMatter	Sep. 30, 2012 Claims that Specify Amount of Damages Sought not Based on Jurisdictional Requirements Legal Claim 1 LegalMatter	Sep. 30, 2012 Claims that Specify Amount of Damages Sought not Based on Jurisdictional Requirements Legal Claim 1 Compensatory	Sep. 30, 2012 Claims that Specify Amount of Damages Sought not Based on Jurisdictional Requirements Legal Claim 1 Punitive	Sep. 30, 2012 Claims that Specify Amount of Damages Sought not Based on Jurisdictional Requirements Legal Claim 2 LegalMatter	Sep. 30, 2012 Claims that Specify Amount of Damages Sought not Based on Jurisdictional Requirements Legal Claim 2 Compensatory	Sep. 30, 2012 Claims that Specify Amount of Damages Sought not Based on Jurisdictional Requirements Legal Claim 2 Punitive	Sep. 30, 2012 Claims that Specify Amount of Damages Sought not Based on Jurisdictional Requirements Legal Claim 3 Punitive	Sep. 30, 2012 Superfund Sites Proceedings LegalMatter	Mar. 31, 2010 PCB Contamination Proceedings	Sep. 30, 2012 PCB Contamination Proceedings	Sep. 30, 2012 PCB Contamination Proceedings Building
Commitments and Contingencies Disclosure [Line Items]
Number of pending claims	315	242				74	239	2			1			1				1
Estimated total cleanup costs, cost sharing percentage																		2.00%
Loss contingency, minimum possible loss																		$ 17.0
Loss contingency, maximum possible loss																		24.0
Estimated total cleanup costs, accrual	0.3
Estimated total cleanup costs, insurance receivable																		0.3
Remediation and monitoring costs incurred since inception related to the PCB soil and building contamination																				2.5	0.8
PCB contamination of the building, liability recording during the period																			1.0	0.2
Percentage of pending claims								1.00%
Damages sought												20	20		65	60	1
Number of defendants				1	833				10	21
Description of named defendants	Cases involving us typically name 50-300 defendants
Number of claims dismissed	70	120
Number of claims settled	11	8
Claims settlements amount	3.6	8.1
Period for recognizing a reserve for future costs	5 years
Cost Sharing Agreement, Expiration Period	4 years
Cost Sharing Agreement, expiration date	Jan. 25, 2015
Asbestos-related liabilities, estimated liability		28.8	27.9
Asbestos-related liabilities, estimated insurance recovery		$ 28.4	$ 27.7