Shareholders Equity and Stock Options (Summary of Activity Under Stock Option Plans) (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013		Dec. 31, 2012	Dec. 31, 2011
Options Outstanding
Options outstanding at beginning of period	1,765,947		2,401,809	2,626,371
Options granted	0		46,950	131,750
Options exercised	(847,340)		(614,263)	(329,964)
Options canceled	(25,468)		(68,549)	(26,348)
Options outstanding at end of period	893,139		1,765,947	2,401,809
Options exercisable at end of period	721,645		1,274,340	1,609,982,000
Options vested or expected to vest at December 31, 2013	887,994	[1]
Weighted-Average Exercise Price Per Share
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
Options exercised	$ 37.82		$ 42.97	$ 33.61
Options cancelled	$ 39.04		$ 43.57	$ 30.77
Outstanding at period end, weighted average grant date fair value	$ 43.23		$ 40.58	$ 37.54
Options exercisable at December 31, 2013	$ 44.62
Options vested or expected to vest at December 31, 2013	$ 43.27	[1]
Weighted-Average Remaining Contractual Life in Years
Options outstanding	3 years 10 months 24 days		1 year 3 months 18 days
Options exercisable at December 31, 2013	3 years 2 months 12 days
Options vested or expected to vest at December 31, 2013	3 years 10 months 24 days	[1]
Aggregate Intrinsic Value
Options outstanding	$ 16,403,816		$ 19,557,233
Options exercisable at December 31, 2013	12,270,104
Options vested or expected to vest at December 31, 2013	$ 16,279,805	[1]

[1] In addition to the vested options, we expect a portion of the unvested options to vest at some point in the future. Options expected to vest are calculated by applying an estimated forfeiture rate to the unvested options.