Employee Benefit Plans (Details 7) (USD $) Share data in Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2012
Summary of time- and market-based RSU activity, Price
Tax benefit realized for the tax deduction from RSUs vested during period	$ 4,902,000	$ 5,356,000	$ 6,294,000
Restricted Stock Units (RSUs)
Summary of time- and market-based RSU activity
RSUs Outstanding, beginning of period (in shares)	4,642	4,125	2,370
Vested (in shares)	(1,560)	(1,097)	(399)
Cancelled or expired (in shares)	(1,158)	(706)	(858)
RSUs Outstanding, end of period (in shares)	6,088	4,642	4,125
Summary of time- and market-based RSU activity, Price
RSUs Outstanding, beginning of period, Price (in dollars per share)	$ 10	$ 13	$ 21
Vested, Price (in dollars per share)	$ 9	$ 11	$ 19
Cancelled or expired, Price (in dollars per share)	$ 15	$ 13	$ 19
RSUs Outstanding, end of period, Price (in dollars per share)	$ 10	$ 10	$ 13
Total pretax intrinsic value of RSUs vested	17,800,000	8,300,000	3,800,000
Tax benefit realized for the tax deduction from RSUs vested during period	$ 4,700,000	$ 1,900,000	$ 900,000
Restricted Stock Units (RSUs) | Minimum
Assumptions applied for the fair value of market-based RSUs using the Monte-Carlo simulation method
Grant date fair value of outstanding RSUs (in dollars per share)	$ 6
Restricted Stock Units (RSUs) | Maximum
Assumptions applied for the fair value of market-based RSUs using the Monte-Carlo simulation method
Grant date fair value of outstanding RSUs (in dollars per share)	$ 20
Time-based RSUs
Summary of time- and market-based RSU activity
Granted (in shares)	3,104	2,219	2,496
Summary of time- and market-based RSU activity, Price
Granted, Price (in dollars per share)	$ 11	$ 7	$ 9
Market-based RSUs
Summary of time- and market-based RSU activity
Granted (in shares)	1,060	101	516
Summary of time- and market-based RSU activity, Price
Granted, Price (in dollars per share)	$ 8	$ 6	$ 11
Assumptions applied for the fair value of market-based RSUs using the Monte-Carlo simulation method
Dividend yield (as a percent)	0.75%	0.00%	0.00%
Risk-free interest rate (as a percent)	1.09%	0.31%	0.99%
Expected volatility (as a percent)	46.00%	47.00%	49.00%
Expected life	2 years 10 months 24 days	3 years	3 years