CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (USD $) In Thousands, except Share data, unless otherwise specified	Total	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Retained Earnings	Treasury Stock
Stockholders' equity at Mar. 31, 2010	$ 571,334	$ 695	$ 428,407	$ 6,272	$ 195,293	$ (59,333)
Common stock, shares outstanding at Mar. 31, 2010		48,870,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	109,243				109,243
Foreign currency translation adjustments	1,613			1,613
Net unrealized gains (losses) on cash flow hedges, net of tax	(6,419)			(6,419)
Net unrealized gain on investments, net of tax	7			7
Stock issued during year under stock-based compensation plans		2,792,000
Proceeds from issuances under stock-based compensation plans	54,301	25	50,428			3,848
Repurchase of restricted common stock (shares)		(26,000)
Repurchase of restricted common stock	0
Cash dividends	(9,703)				(9,703)
Stock-based compensation	15,873		15,873
Tax benefit from stock-based awards	4,319		4,319
Repurchase of common stock (shares)		(3,315,000)
Repurchase of common stock	(105,522)					(105,522)
Employees' tax withheld and paid for restricted stock and restricted stock units (shares)		(6,000)
Employees' tax withheld and paid for restricted stock and restricted stock units	(194)					(194)
Retirement of treasury stock	(102,365)				(102,365)	102,365
Stockholders' equity at Mar. 31, 2011	634,852	720	499,027	1,473	192,468	(58,836)
Common stock, shares outstanding at Mar. 31, 2011		48,315,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	109,036				109,036
Foreign currency translation adjustments	(788)			(788)
Net unrealized gains (losses) on cash flow hedges, net of tax	5,618			5,618
Net unrealized gain on investments, net of tax	54			54
Stock issued during year under stock-based compensation plans	2,359,000
Proceeds from issuances under stock-based compensation plans	43,123	21	37,415			5,687
Repurchase of restricted common stock (shares)		(60,000)
Repurchase of restricted common stock	0	0
Cash dividends	(9,040)				(9,040)
Stock-based compensation	17,481		17,481
Tax benefit from stock-based awards	3,295		3,295
Repurchase of common stock (shares)		(8,027,000)
Repurchase of common stock	(273,791)					(273,791)
Employees' tax withheld and paid for restricted stock and restricted stock units (shares)		(75,000)
Employees' tax withheld and paid for restricted stock and restricted stock units	(2,596)					(2,596)
Retirement of treasury stock	(177,106)				(177,106)	177,106
Stockholders' equity at Mar. 31, 2012	527,244	741	557,218	6,357	115,358	(152,430)
Common stock, shares outstanding at Mar. 31, 2012		42,512,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	106,402				106,402
Foreign currency translation adjustments	(261)			(261)
Net unrealized gains (losses) on cash flow hedges, net of tax	(555)			(555)
Net unrealized gain on investments, net of tax	26			26
Stock issued during year under stock-based compensation plans		1,730,000
Proceeds from issuances under stock-based compensation plans	31,865	16	29,289			2,560
Repurchase of restricted common stock (shares)		(114,000)
Repurchase of restricted common stock	0	0
Cash dividends	(17,072)				(17,072)
Stock-based compensation	18,350		18,350
Tax benefit from stock-based awards	1,260		1,260
Repurchase of common stock (shares)		(752,000)
Repurchase of common stock	(23,931)					(23,931)
Employees' tax withheld and paid for restricted stock and restricted stock units (shares)		(93,000)
Employees' tax withheld and paid for restricted stock and restricted stock units	(3,047)					(3,047)
Adjustment related to expired stock options			6,166
Retirement of treasury stock	(176,344)				176,344	(176,344)
Stockholders' equity at Mar. 31, 2013	$ 646,447	$ 757	$ 612,283	$ 5,567	$ 28,344	$ (504)
Common stock, shares outstanding at Mar. 31, 2013		43,283,000