Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2018	Mar. 31, 2017
Earnings Per Share [Abstract]
Income from continuing operations	$ 178,992	$ 162,012	$ 493,124	$ 276,050
Income allocated to participating securities	161	193	459	348
Income from continuing operations available to common shareholders	$ 178,831	$ 161,819	$ 492,665	$ 275,702
Income (Loss) from Continuing Operations, Per Basic and Diluted Share	$ 1.60	$ 1.52	$ 4.47	$ 2.61
Income from discontinued operations, net of tax	$ 0	$ 2,716	$ 0	$ 13,710
Undistributed Earnings From Discontinued Operations Allocated To Participating Securities	0	2	0	15
Income from discontinued operations available to common shareholders	$ 0	$ 2,714	$ 0	$ 13,695
Income (Loss) from Discontinued Operation, Net of Tax, Per Basic and Diluted Share	$ 0.00	$ 0.03	$ 0.00	$ 0.13
Basic and diluted net income per share	$ 1.60	$ 1.55	$ 4.47	$ 2.74
Weighted Average Number of Shares Outstanding, Basic and Diluted	111,706	105,935	110,135	105,610