Stock Repurchases (Details) (USD $) In Thousands, except Share data	3 Months Ended		6 Months Ended		9 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010	Dec. 31, 2010
Stock Repurchases
Shares remained available for repurchase	1,736,725		1,736,725
Number of shares	1,100,000	1,000,000	3,100,000	1,952,500
Total Cost	$ 79,423	$ 105,034	$ 218,520	$ 200,059	$ 234,597
Average cost per share	$ 72.20	$ 105.03	$ 70.49	$ 102.46