Earnings Per Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2013	Mar. 31, 2012
Earnings Per Share [Abstract]
Numerator: Net income	$ 13,978	$ 14,756	$ 47,977	$ 54,503
Weighted-average shares outstanding, basic (in shares)	27,847,000	27,489,000	27,725,000	27,290,000
Denominator: Dilutive effect of share-based payments	177,000	437,000	235,000	419,000
Weighted-average shares outstanding, diluted (in shares)	28,024,000	27,926,000	27,960,000	27,709,000
Net income per common share, basic (in dollars per share)	$ 0.50	$ 0.54	$ 1.73	$ 2.00
Net income per common share, diluted (in dollars per share)	$ 0.50	$ 0.53	$ 1.72	$ 1.97
Weighted average shares excluded from the computation of diluted earnings per share	1,119,940	260,901	1,097,610	597,872