Current and Deferred Income Tax Expense (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Deferred Income Tax Assets And Liabilities
Income before income taxes	$ 32,843	$ 14,669
Current tax expense	10,223	4,053
Deferred tax expense	3,332	864
Total tax expense	$ 13,555	$ 4,917