Earnings Per Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2014	Mar. 31, 2013
Earnings Per Share [Abstract]
Numerator: Net income	$ 16,949	$ 13,978	$ 54,684	$ 47,977
Weighted-average shares outstanding, basic (in shares)	28,502,000	27,847,000	28,275,000	27,725,000
Dilutive effect of share-based payments	228,000	177,000	273,000	235,000
Weighted-average shares outstanding, diluted (in shares)	28,730,000	28,024,000	28,548,000	27,960,000
Net income per common share, basic (in dollars per share)	$ 0.59	$ 0.50	$ 1.93	$ 1.73
Net income per common share, diluted (in dollars per share)	$ 0.59	$ 0.50	$ 1.92	$ 1.72
Weighted average shares excluded from the computation of diluted earnings per share	275,635	1,119,940	203,384	1,097,610