Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Earnings Per Share [Abstract]
Net income (loss)	$ 71,193	$ 56,281	$ 315,864	$ 291,560
Income allocated to participating securities	108	111	496	596
Income available to common shareholders	$ 71,085	$ 56,170	$ 315,368	$ 290,964
Basic and diluted net income per share	$ 0.69	$ 0.55	$ 3.06	$ 2.86
Weighted Average Number of Shares Outstanding, Basic and Diluted	103,750	102,000	103,137	101,776