Stockholders' Equity (Narrative) (Details) - USD ($)	12 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Mar. 31, 2014
Cash received from option exercises and purchases of shares under the Purchase Plans	$ 4,800,000	$ 4,500,000	$ 5,200,000
Stock-Based Awards
Total intrinsic value of options exercised	9,200,000	$ 8,100,000	8,200,000
Unamortized stock-based compensation expense related to unvested stock awards	34,800,000
Weighted average period of recognition for unrecognized compensation costs (in years)		2 years 212 days
Tax benefit attributable to stock options exercised	$ 224,000	$ 151,000	$ 142,000
Employee Stock Purchase Plan
Employee Stock Purchase Plan Shares Issued	365,555	282,062	301,303
Percentage of market value price of common stock under Employee Stock Purchase Plan		85.00%
Maximum contribution percentage amount of employee's base compensation		10.00%