Condensed Consolidated Statement Of Comprehensive Income (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Statement of Comprehensive Income [Abstract]
Net income	$ 89,981	$ 51,711	$ 248,331	$ 176,645
Other comprehensive gains (losses), net of tax:
Unrealized holding gain (loss)	51	(822)	3	(2,316)
Reclassification adjustment for loss included in net income	441	266	1,316	1,200
Total other comprehensive gain (loss)	492	(556)	1,319	(1,116)
Comprehensive income	$ 90,473	$ 51,155	$ 249,650	$ 175,529