Stockholders' Equity (Details) (USD $)	3 Months Ended		9 Months Ended		1 Months Ended	9 Months Ended			1 Months Ended
	Apr. 30, 2014	Oct. 31, 2013	Apr. 30, 2014	Apr. 30, 2013	Jun. 04, 2014 Subsequent	Apr. 30, 2014 Quarterly Dividend - First	Apr. 30, 2014 Quarterly Dividend - Second	Apr. 30, 2014 Quarterly Dividend - Third	Jun. 30, 2014 Quarterly Dividend - Fourth Subsequent	Jun. 05, 2014 Quarterly Dividend - Fourth Subsequent
Stock Repurchase Program
Shares acquired			1,851,303	940,293
Average price per share of shares repurchased on the open market			$ 31.40	$ 25.77
Aggregate cost including transaction costs			$ 58,122,000	$ 24,232,000
Maximum amount authorized by the Board of Directors for repurchases of the Company's common stock			100,000,000
Stock repurchase program, remaining authorized repurchase amount			$ 26,249,000		$ 14,250,000
Dividends
Targeted annual dividend per share	$ 1.20	$ 1.10
Date declared						Oct. 03, 2013	Dec. 09, 2013	Mar. 06, 2014	Jun. 05, 2014
Date of record									Jul. 18, 2014
Date paid						Nov. 19, 2013	Feb. 19, 2014	May 30, 2014	Aug. 19, 2014
Quarterly dividend payment amount per share						$ 0.275	$ 0.30	$ 0.30		$ 0.30