Quarterly Operating Results (Unaudited) - Additional Information (Detail) (USD $)	3 Months Ended			12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Dec. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Effect of Fourth Quarter Events [Line Items]
Asset impairment charges	$ 3,700,000	$ 30,000,000	$ 2,500,000	$ (33,676,000)	$ (2,549,000)	$ (16,574,000)
Severance charges	500,000	17,400,000	5,000,000
Losses on the extinguishment of debt	$ 1,900,000	$ 50,600,000		$ (52,450,000)