Divestiture - Results of Discontinued Operations (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2013	Mar. 31, 2012
Discontinued Operations And Disposal Groups [Abstract]
Revenues		$ 61,879	$ 20,196	$ 117,853
(Loss) income from discontinued operations before income taxes	(1,660)	23,453	569,863	45,221
Less income tax (benefit) provision	(1,177)	7,544	215,160	14,871
(Loss) income from discontinued operations, net	$ (483)	$ 15,909	$ 354,703	$ 30,350