Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended		9 Months Ended
	Feb. 18, 2014	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Earnings Per Share [Abstract]
Net income (loss)		$ 56,281	$ 45,721	$ 291,560	$ 266,104
Stock Issued During Period, Shares, New Issues	9,200,000
Shares Issued At Overallotment Option	1,200,000
Share Price	$ 44.00
Net proceeds from equity offering	$ 390,200			0	390,205
Basic Earnings per Share from Continuing Operations
Undistributed Earnings (Loss) Allocated to Participating Securities, Basic		111	106	596	667
Income from continuing operations available to common shareholders		$ 56,170	$ 45,615	$ 290,964	$ 265,437
Basic weighted average shares outstanding		102,000,000	101,162,000	101,776,000	96,392,000
Net income per share - Basic		$ 0.55	$ 0.45	$ 2.86	$ 2.76
Diluted Earnings per Share from Continuing Operations
Income from continuing operations available to common shareholders		$ 56,170	$ 45,615	$ 290,964	$ 265,437
Effect of dilutive stock options and other shares		0	0	0	0
Income from continuing operations available to common shareholders		$ 56,170	$ 45,615	$ 290,964	$ 265,437
Basic weighted average shares outstanding		102,000,000	101,162,000	101,776,000	96,392,000
Additional dilutive stock options and other shares		0	1,000	0	2,000
Diluted weighted average shares outstanding		102,000,000	101,163,000	101,776,000	96,394,000
Net income per share - Diluted		$ 0.55	$ 0.45	$ 2.86	$ 2.76
Earnings Per Share Diluted Other Disclosures Abstract
Anti-dilutive stock options excluded from computation of diluted earnings per share (in shares)			0		0
Share Repurchase Program - Shares Purchased				0	0
Summary of Stock Option Activity [Abstract]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number		0		0