Consolidated Statements of Shareholders' Equity (USD $) In Thousands, unless otherwise specified	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Loss
Beginning Balance at Mar. 31, 2010	$ 188,289	$ 578	$ 121,982	$ 65,729	$ 0
Beginning Balance, Shares at Mar. 31, 2010		57,758
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options and vesting of restricted stock	5,717	3	5,714
Exercise of stock options and vesting of restricted stock, Shares	(307)	310
Tax benefit resulting from exercise of stock options	1,524		1,524
Stock-based compensation	3,748		3,748
Dividends declared	(36,214)			(36,214)
Unrealized loss on AFS securities	0
Translation adjustments	0
Net income	61,606			61,606
Ending Balance at Mar. 31, 2011	224,670	581	132,968	91,121
Ending Balance, Shares at Mar. 31, 2011		58,068
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options and vesting of restricted stock	12,790	7	12,783
Exercise of stock options and vesting of restricted stock, Shares	(697)	735
Common stock issuance for Opus earnout settlement	11,888	3	11,885
Common stock issuance for Opus earnout settlement, Shares		286
Tax benefit resulting from exercise of stock options	4,145		4,145
Stock-based compensation	3,321		3,321
Common stock issuance for acquisitions	3,932	1	3,931
Common stock issuance for acquisitions, Shares		91
Dividends declared	(41,181)			(41,181)
Unrealized loss on AFS securities	(42)				(42)
Translation adjustments	(3)				(3)
Net income	75,657			75,657
Ending Balance at Mar. 31, 2012	295,177	592	169,033	125,597	(45)
Ending Balance, Shares at Mar. 31, 2012		59,180
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options and vesting of restricted stock	948	1	947
Exercise of stock options and vesting of restricted stock, Shares	(56)	83
Common stock issuance for Opus earnout settlement	3,000	1	2,999
Common stock issuance for Opus earnout settlement, Shares		165
Tax benefit resulting from exercise of stock options	(157)		(157)
Stock-based compensation	2,327		2,327
Common stock issuance for acquisitions	4,595	1	4,594
Common stock issuance for acquisitions, Shares		115
Dividends declared	(41,599)			(41,599)
Unrealized loss on AFS securities	0
Translation adjustments	34				34
Net income	42,724			42,724
Ending Balance at Mar. 31, 2013	$ 307,049	$ 595	$ 179,743	$ 126,722	$ (11)
Ending Balance, Shares at Mar. 31, 2013		59,543