Net Income Per Share (Details) (USD $) In Thousands, except Per Share data	3 Months Ended		12 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Jun. 30, 2011
Net Income Per Share
Net income	$ 191,995	$ 154,196
Denominator:
Weighted average shares-basic, excluding unvested restricted stock units	166,684	167,187
Effect of dilutive options and restricted stock units	3,151	2,652
Weighted-average shares-diluted	169,835	169,839
Basic net income per share	$ 1.15	$ 0.92
Diluted net income per share	$ 1.13	$ 0.91
Anti-dilutive securities excluded from the computation of diluted net income per share	6,635	10,340
Payments of dividends	$ 58,460	$ 41,785
Common stock quarterly dividends per share authorized	$ 0.35		$ 0.25