Stock-Based Compensation - Stock Option Transactions (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	6 Months Ended	12 Months Ended
	Sep. 30, 2012	Apr. 01, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Balance at April 1, 2012, Weighted Average Exercise Price per Share	$ 7.23
Granted, Weighted Average Exercise Price per Share	$ 7.91
Exercised, Weighted Average Exercise Price per Share	$ 6.72
Cancelled, Weighted Average Exercise Price per Share	$ 10.65
Forfeited, Weighted Average Exercise Price per Share	$ 6.30
Balance at September 30, 2012, Weighted Average Exercise Price per Share	$ 7.38	$ 7.23
Vested and expected to vest, September 30, 2012, Weighted Average Exercise Price per Share	$ 7.42
Vested and exercisable, September 30, 2012, Weighted Average Exercise Price per Share	$ 8.18
Weighted Average Remaining Contractual Term (in years)	4 years 8 months 12 days	4 years 8 months 1 day
Vested and expected to vest, September 30,2012, Weighted Average Remaining Contractual Term (in years)	4 years 5 months 27 days
Vested and exercisable to vest, September 30,2012, Weighted Average Remaining Contractual Term (in years)	2 years 4 months 17 days
Balance at April 1, 2012, Aggregate Intrinsic Value	$ 9,474
Balance at September 30, 2012, Aggregate Intrinsic Value	5,950	9,474
Vested and expected to vest, September 30, 2012, Aggregate Intrinsic Value	5,251
Vested and exercisable, September 30, 2012, Aggregate Intrinsic Value	1,514
Balance at April 1, 2012, In-the-money Options Vested and Exercisable	1,193
Balance at September 30, 2012, In-the-money Options Vested and Exercisable	$ 1,081	$ 1,193
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Balance at April 1, 2012, Outstanding	6,345,307
Granted, Outstanding	1,259,700
Exercised, Outstanding	(455,946)
Cancelled, Outstanding	(249,551)
Forfeited, Outstanding	(703,062)
Balance at September 30, 2012, Outstanding	6,196,448
Vested and expected to vest, September 30, 2012, Outstanding	5,487,339
Vested and exercisable, September 30, 2012, Outstanding	2,268,140