Stockholders' Equity (Changes In Stockholders' Equity) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2011		Dec. 31, 2010
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at March 31, 2011			$ 1,734,882
Comprehensive income:
Net earnings	72,305	55,831	224,849		187,195
Foreign currency translation adjustments			(5,023)
Amount of gain (loss) recognized in OCI, pre-tax			388
Tax effect of comprehensive income items			(144)
Total comprehensive income			220,070	[1]	189,000
Common stock issuances and reissuances from treasury stock - employee benefit plans			34,251	[2]
Tax benefit from stock option exercises			9,404
Payments of Dividends, Common Stock			(70,819)		(60,340)
Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition			21,352	[3]
Dividends paid on common stock (per share)			$ 0.93
Purchase of treasury stock			300,000	[4]
Balance at December 31, 2011	1,649,140		1,649,140
Treasury Stock Acquired, Average Cost Per Share			$ 67.19
Treasury Stock, Value, Acquired, Cost Method			300,000	[4]
Common Stock [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at March 31, 2011			866
Common stock, beginning balance (shares)			86,591
Comprehensive income:
Common stock issuance (shares)			210	[5]
Common stock issuances and reissuances from treasury stock - employee benefit plans			2	[2]
Reissuance of treasury stock for stock option exercises (shares)			0
Purchase of treasury stock (shares)			0	[4]
Common stock, ending balance (shares)	86,801		86,801
Balance at December 31, 2011	868		868
Capital In Excess Of Par Value [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at March 31, 2011			607,593
Comprehensive income:
Common stock issuances and reissuances from treasury stock - employee benefit plans			(3,548)	[2]
Tax benefit from stock option exercises			9,404
Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition			21,352	[3]
Balance at December 31, 2011	634,801		634,801
Retained Earnings [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at March 31, 2011			1,498,728
Comprehensive income:
Net earnings			224,849
Common stock issuances and reissuances from treasury stock - employee benefit plans			(11,013)	[2]
Payments of Dividends, Common Stock			(70,819)
Balance at December 31, 2011	1,641,745		1,641,745
Accumulated Other Comprehensive Income (Loss) [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at March 31, 2011			7,580
Comprehensive income:
Foreign currency translation adjustments			(5,023)
Balance at December 31, 2011	2,801		2,801
Treasury Stock [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at March 31, 2011			(379,885)
Treasury stock, beginning balance (shares)			6,995
Comprehensive income:
Common stock issuance (shares)			0	[5]
Common stock issuances and reissuances from treasury stock - employee benefit plans			48,810	[2]
Reissuance of treasury stock for stock option exercises (shares)			(848)
Purchase of treasury stock			(300,000)	[4]
Purchase of treasury stock (shares)			4,465	[4]
Treasury stock, ending balance (shares)	10,611		10,611
Balance at December 31, 2011	(631,075)		(631,075)
Treasury Stock, Value, Acquired, Cost Method			(300,000)	[4]
Interest Rate Lock Commitments [Member] | Accumulated Other Comprehensive Income (Loss) [Member]
Comprehensive income:
Amount of gain (loss) recognized in OCI, pre-tax			388
Interest Rate Lock Commitments [Member] | Cash Flow Hedging [Member]
Comprehensive income:
Amount of gain (loss) recognized in OCI, pre-tax			388		1,504
Interest Rate Lock Commitments [Member] | Tax Effect [Member] | Cash Flow Hedging [Member] | Accumulated Other Comprehensive Income (Loss) [Member]
Comprehensive income:
Tax effect of comprehensive income items			$ 144

[1] The Company’s comprehensive income was $220 million and $189 million for the nine months ended December 31, 2011 and 2010, respectively. Comprehensive income consists of net earnings, foreign currency translation adjustments, net gain on derivative instruments designated as cash flow hedges and the net tax effect of other comprehensive income items. Net tax effect of comprehensive income items pertains to the Company’s derivative instruments only, as foreign currency translation adjustments relate to permanent investments in foreign subsidiaries. The net gain on derivative instruments reflects reclassification adjustments to income.

[2] Issuance of common stock for purchases through the Employee Stock Purchase Plan and reissuance of treasury stock for stock option exercises.

[3] The Company recognized compensation expense with a corresponding amount recorded to capital in excess of par value.

[4] As of December 31, 2011, the Company had completed a $300 million share repurchase authorization announced on May 5, 2011, repurchasing 4.5 million shares on the open market at an average price of $67.19.

[5] Issuance of common stock for purchases through the Employee Stock Purchase Plan.