Shareholders Equity and Stock Options (Performance Based Restricted Stock Awards) (Detail) (USD $)	3 Months Ended	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Jun. 30, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Beginning Balance		$ 37.54	$ 36.63	$ 38.40	$ 37.54
Options granted	$ 41.27	$ 41.27	$ 46.29	$ 24.26
Options exercised	$ 42.97	$ 42.97	$ 33.61	$ 31.33
Options cancelled	$ 43.57	$ 43.57	$ 30.77	$ 38.92
Ending Balance	$ 40.58	$ 40.58	$ 37.54	$ 36.63	$ 37.54
Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Non-vested awards outstanding, beginning balance		101,730	115,250	98,400
Beginning Balance		$ 31.19	$ 27.09	$ 32.29
Awards granted		22,120	20,630	37,350
Options granted		$ 41.27	$ 47.89	$ 27.43
Stock issued		(43,750)	0	0
Options exercised		$ 23.86	$ 0.00	$ 0.00
Awards forfeited or expired		(6,642)	(34,150)	(20,500)
Options cancelled		$ 37.67	$ 27.43	$ 52.66
Non-vested awards outstanding, ending balance	73,458	73,458	101,730	115,250
Ending Balance	$ 38.01	$ 38.01	$ 31.19	$ 27.09