Reconciliation of Basic and Diluted Net Income (Loss) Per Common Share (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2012	Dec. 31, 2011
Numerator:
Net income (loss)	$ (14,257)	$ (27,771)	$ (56,931)	$ 18,396
Weighted-average shares outstanding:
Basic (in shares)	44,918	44,644	44,879	42,834
Assumed conversion of employee stock options (in shares)				294
Assumed conversion of warrants (in shares)				9,174
Diluted (in shares)	44,918	44,644	44,879	52,302
Net income (loss) per share:
Basic (in dollars per share)	$ (0.32)	$ (0.62)	$ (1.27)	$ 0.43
Diluted (in dollars per share)	$ (0.32)	$ (0.62)	$ (1.27)	$ 0.35