Stock-Based Compensation (Stock-Based Compensation Expense) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2012	Dec. 31, 2011
Stock-based compensation expense related to:
Equity Incentive Plan	$ 3,528	$ 3,311	$ 19,682	$ 18,450
Employee Stock Purchase Plan - options to purchase stock	1,024	971	3,062	2,902
Stock-based compensation expense	4,552	4,282	22,744	21,352
Tax benefit	(1,443)	(1,410)	(7,826)	(7,370)
Stock-based compensation expense, net of tax	$ 3,109	$ 2,872	$ 14,918	$ 13,982