Share-Based Compensation Including Expense for Phantom Stock Units and Cash Settled Stock Appreciation Rights Granted to Employees (Detail) (USD $)	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Cost of employee share-based compensation included in income, before income tax	$ 1,319,000	$ 2,865,000
Cost of Sales
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Cost of employee share-based compensation included in income, before income tax	80,000	80,000
Operating Expense
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Cost of employee share-based compensation included in income, before income tax	$ 1,239,000	$ 2,785,000