Restructuring Activities - Additional Information (Detail) (USD $)			12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2012 Canonsburg, Pennsylvania Person	Dec. 31, 2011 Tulsa, Oklahoma Person	Dec. 31, 2010 Kingsport, Tennessee Person	Dec. 31, 2012 Accounts Payable and Accrued Liabilities	Dec. 31, 2012 Other Noncurrent Liabilities
Restructuring Cost and Reserve [Line Items]
Organization restructuring, termination of employees			30	40	30
Estimated discounted future net cash outflows over remainder of contract			$ 17,300,000
Restructuring and related costs in 2013			2,800,000
Restructuring and related costs in 2014			2,800,000
Restructuring and related costs in 2015			2,800,000
Restructuring and related costs in 2016			2,800,000
Restructuring and related costs in 2017			2,800,000
Restructuring and related costs due 2018 - 2022			13,000,000
Restructuring reserve, current						2,700,000
Restructuring reserve, noncurrent	$ 14,333,000	$ 0					$ 14,500,000