Quarterly Financial Information Pre-Tax Charges (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Condensed Financial Statements, Captions [Line Items]
Impairment losses	$ 2,551				$ 374,846		$ 1,697	$ 782	$ 2,551	$ 377,325	$ 4,799
Restructuring charge (benefit)	$ (91)	$ 18	$ 18	$ 55	$ 797	$ 348	$ 5,926	$ 4,476		$ 11,547	$ 5,251