Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Cash flows provided by operating activities:
Net income	$ 19,307	$ 14,237
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	6,509	6,169
Share-based compensation expense	4,181	3,858
Gain on sale of property and equipment	(109)	(6)
Foreign currency losses, net	244	64
Net change in operating assets and liabilities:
Accounts receivable, net	(8,911)	(15,348)
Prepaid expenses and other current assets	(1,412)	(322)
Other long-term assets	(39)	(3,503)
Accounts payable	614	(2,514)
Accrued employee compensation and benefits	(1,435)	2,657
Accrued expenses and other current liabilities	2,431	2,553
Income taxes payable	2,399	2,652
Other long-term liabilities	(99)	(732)
Net cash provided by operating activities	23,680	9,765
Cash flows used for investing activities:
Proceeds from sale of property and equipment	117	114
Purchase of short-term investments	(8,571)	(6,638)
Proceeds from sale or maturity of short-term investments	7,975	30,979
Purchase of long-term investments	(8,421)	(5,202)
Proceeds from sale or maturity of long-term investments	1,258	10,406
Business acquisition	(2,775)	(25,055)
Decrease (increase) in restricted cash	2,426	(2,678)
Purchase of property and equipment	(8,517)	(10,223)
Net cash used for investing activities	(16,508)	(8,297)
Cash flows used for financing activities:
Proceeds from exercise of common stock options	710	1,740
Purchase of treasury stock	(1,408)
Payment of contingent consideration related to acquisition		(1,620)
Principal payments on capital lease obligation	(1,021)	(932)
Net cash used for financing activities	(1,719)	(812)
Effect of exchange rate changes on cash and cash equivalents	(935)	(1,939)
Net increase (decrease) in cash and cash equivalents	4,518	(1,283)
Cash and cash equivalents, beginning of period	58,105	50,218
Cash and cash equivalents, end of period	$ 62,623	$ 48,935