Income Taxes Narrative (Detail) - USD ($) $ in Thousands	3 Months Ended			6 Months Ended
	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015	Mar. 31, 2016	Mar. 31, 2015
Income Tax Contingency [Line Items]
Income tax provision (benefit)	$ 78,220		$ 1,560	$ 74,850	$ (1,550)
Establishment of a valuation allowance	79,300	$ 79,300
Reductions in unrecognized tax benefits from expiration					600
Income tax benefit resulted from reinstatement of tax credit					$ 900
Minimum
Income Tax Contingency [Line Items]
Anticipated unrecognized tax benefit reduction during next twelve months	$ 1,200			$ 1,200