Shareholders Equity and Stock Options (Deferred Stock Units) (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Outstanding at period beginning, weighted average grant date fair value	$ 40.58	$ 37.54	$ 36.63
Awards granted, weighted average grant date fair value	$ 0.00	$ 41.27	$ 46.29
Stock issued, weighted average grant date fair value	$ 37.82	$ 42.97	$ 33.61
Outstanding at period end, weighted average grant date fair value	$ 43.23	$ 40.58	$ 37.54
Deferred Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Non-vested awards outstanding, beginning balance	30,150	27,350	30,250
Awards granted	16,800	17,600	16,650
Stock issued	(15,400)	(14,800)	(19,550)
Non-vested awards outstanding, ending balance	31,550	30,150	27,350
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Outstanding at period beginning, weighted average grant date fair value	$ 26.13	$ 28.80	$ 28.98
Awards granted, weighted average grant date fair value	$ 41.67	$ 38.64	$ 45.95
Stock issued, weighted average grant date fair value	$ 41.77	$ 45.95	$ 43.69
Outstanding at period end, weighted average grant date fair value	$ 26.77	$ 26.13	$ 28.80