Net Income (Loss) Per Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2012
Net Income (Loss) per Share
Net income (loss)	$ 74,304	$ (227,518)	$ 104,237
Shares used in net income (loss) per share computation:
Weighted average shares outstanding - basic	160,619,000	158,468,000	174,648,000
Effect of potentially dilutive equivalent shares	1,907,000		943,000
Weighted average shares outstanding - diluted	162,526,000	158,468,000	175,591,000
Net income (loss) per share:
Basic (in dollars per share)	$ 0.46	$ (1.44)	$ 0.60
Diluted (in dollars per share)	$ 0.46	$ (1.44)	$ 0.59
Anti-dilutive equivalents shares excluded	15,091,478	22,859,941	18,431,855