Consolidated Statements of Stockholders' Equity (USD $) In Thousands, except Share data, unless otherwise specified	Total	Common Stock [Member]	Capital In Excess of Par Value [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income [Member]	Treasury Stock [Member]
Total stockholders' equity at period start date at Mar. 31, 2010	$ 1,801,076	$ 863	$ 568,421	$ 1,338,291	$ 3,442	$ (109,941)
Treasury stock at period start date, shares at Mar. 31, 2010						(3,027,000)
Common stock, issued at period start date, shares at Mar. 31, 2010		86,253,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	250,264			250,264
Foreign currency translation adjustments	2,948				2,948
Net gain on derivative instruments (Note 10)	1,633				1,633
Net tax expense of other comprehensive income items	(443)				(443)
Treasury stock reissuances in connection with stock options exercised (Note 13)	22,092		(7,964)			30,056
Treasury stock reissuances in connection with stock options exercised (Note 13), shares						812,000
Dividends paid on common stock (Note 12)	(83,797)			(83,797)
Excess tax benefit associated with the exercise of stock options	8,444		8,444
Shares issued in connection with the Employee Stock Purchase Plan, Shares (Note 13)		338,000
Shares issued in connection with the Employee Stock Purchase Plan (Note 13)	14,997	3	14,994
Stock-based compensation expense (Note 13)	23,698		23,698
Purchase of treasury stock (Note 12)	(300,000)					(300,000)
Purchase of treasury stock (Note 12), shares	(4,780,000)					(4,780,000)
Common Stock, Dividends, Per Share, Cash Paid	$ 1.01
Total stockholders' equity at period end date at Mar. 31, 2011	1,740,912	866	607,593	1,504,758	7,580	(379,885)
Treasury stock at period end date, shares at Mar. 31, 2011						(6,995,000)
Common stock, issued at period end date, shares at Mar. 31, 2011		86,591,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	313,374			313,374
Foreign currency translation adjustments	(2,520)				(2,520)
Net gain on derivative instruments (Note 10)	517				517
Net tax expense of other comprehensive income items	(191)				(191)
Treasury stock reissuances in connection with stock options exercised (Note 13)	36,619		(14,909)	(21,331)		72,859
Treasury stock reissuances in connection with stock options exercised (Note 13), shares						1,253,000
Dividends paid on common stock (Note 12)	(95,323)			(95,323)
Excess tax benefit associated with the exercise of stock options	16,006		16,006
Shares issued in connection with the Employee Stock Purchase Plan, Shares (Note 13)		283,000
Shares issued in connection with the Employee Stock Purchase Plan (Note 13)	15,256	3	15,253
Stock-based compensation expense (Note 13)	25,608		25,608
Purchase of treasury stock (Note 12)	(300,000)					(300,000)
Purchase of treasury stock (Note 12), shares	(4,465,000)					(4,465,000)
Common Stock, Dividends, Per Share, Cash Paid	$ 1.25
Total stockholders' equity at period end date at Mar. 31, 2012	1,750,258	869	649,551	1,701,478	5,386	(607,026)
Treasury stock at period end date, shares at Mar. 31, 2012	(10,207,000)					(10,207,000)
Common stock, issued at period end date, shares at Mar. 31, 2012	86,874,000	86,874,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	340,874			340,874
Foreign currency translation adjustments	(1,274)				(1,274)
Net gain on derivative instruments (Note 10)	517				517
Net tax expense of other comprehensive income items	(191)				(191)
Treasury stock reissuances in connection with stock options exercised (Note 13)	88,700			(58,755)		147,455
Treasury stock reissuances in connection with stock options exercised (Note 13), shares						2,421,000
Dividends paid on common stock (Note 12)	(122,202)			(122,202)
Excess tax benefit associated with the exercise of stock options	36,160		36,160
Shares issued in connection with the Employee Stock Purchase Plan, Shares (Note 13)		261,000
Shares issued in connection with the Employee Stock Purchase Plan (Note 13)	17,088	2	17,086
Stock-based compensation expense (Note 13)	27,053		27,053
Purchase of treasury stock (Note 12)	(600,000)					(600,000)
Purchase of treasury stock (Note 12), shares	(6,291,000)					(6,291,000)
Common Stock, Dividends, Per Share, Cash Paid	$ 1.60
Total stockholders' equity at period end date at Mar. 31, 2013	$ 1,536,983	$ 871	$ 729,850	$ 1,861,395	$ 4,438	$ (1,059,571)
Treasury stock at period end date, shares at Mar. 31, 2013	(14,077,000)					(14,077,000)
Common stock, issued at period end date, shares at Mar. 31, 2013	87,135,000	87,135,000