CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2013
Statement of Comprehensive Income [Abstract]
Net income	$ 432,573	$ 340,822	$ 350,224
Derivative financial instruments:
Unrealized holding gain (losses)	(4,061)	4,208	(244)
Gains/(losses) reclassified to net income	(228)	834	1,774
Total other comprehensive income (loss)	(4,289)	5,042	1,530
Comprehensive income	$ 428,284	$ 345,864	$ 351,754