Earnings Per Share - Schedule of Calculation of Basic and Diluted Earnings per Share of Common Stock Outstanding (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2013	Dec. 31, 2012
Earnings Per Share [Abstract]
Net income	$ 71,629	$ 47,489	$ 118,081	$ 102,044
Weighted average shares outstanding, basic	68,715	69,009	69,131	68,846
Employee stock options	863	725	816	736
Weighted average shares outstanding, diluted	69,578	69,734	69,947	69,582
Earnings per share, basic	$ 1.04	$ 0.69	$ 1.71	$ 1.48
Earnings per share, diluted	$ 1.03	$ 0.68	$ 1.69	$ 1.47