Earnings Per Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2012	Dec. 31, 2011
Earnings Per Share [Abstract]
Numerator: Net income	$ 16,357	$ 21,367	$ 33,999	$ 39,746
Denominator: Weighted-average shares, basic	27,713,000	27,244,000	27,665,000	27,191,000
Denominator: Dilutive effect of share-based payments	245,000	430,000	263,000	413,000
Denominator: Weighted-average shares, diluted	27,958,000	27,674,000	27,928,000	27,604,000
Net income per common share, basic (in dollars per share)	$ 0.59	$ 0.78	$ 1.23	$ 1.46
Net income per common share, diluted (in dollars per share)	$ 0.59	$ 0.77	$ 1.22	$ 1.44
Weighted average shares excluded from the computation of diluted earnings per share	1,159,357	622,247	1,112,076	722,315