Carrying amount as of the balance sheet date of known and estimated obligations associated with exit from or disposal of business activities or restructurings pursuant to a duly authorized plan, which are expected to be paid in the next twelve months or in the normal operating cycle if longer. Costs of such activities include those for one-time termination benefits, termination of an operating lease or other contract, consolidating or closing facilities, relocating employees, and costs associated with an ongoing benefit arrangement, but excludes costs associated with the retirement of a long-lived asset.

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Carrying amount as of the balance sheet date of known and estimated costs associated with exit from or disposal of business activities or restructurings pursuant to a duly authorized plan, which are expected to be paid after one year or beyond the next operating cycle, if longer. Costs of such activities include those for one-time termination benefits, termination of an operating lease or other contract, consolidating or closing facilities, and relocating employees, and costs associated with an ongoing benefit arrangement, but excludes costs associated with the retirement of a long-lived asset.

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Restructuring and Exit Activities - Additional Information (Detail) (USD $)					12 Months Ended
	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2013 Accounts Payable and Accrued Liabilities	Mar. 31, 2013 Other Noncurrent Liabilities	Dec. 31, 2012 Canonsburg, Pennsylvania Person
Restructuring Cost and Reserve [Line Items]
Organization restructuring, termination of employees					30
Restructuring reserve, current			$ 3,000,000
Restructuring reserve, noncurrent	$ 13,870,000	$ 14,333,000		$ 14,000,000