Stockholders' Equity (Stock Repurchase Programs) (Details) (USD $) In Thousands, except Share data in Millions, unless otherwise specified	12 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2012
Stockholders' Equity Note [Abstract]
Stock repurchase program, authorized amount		$ 600,000	$ 300,000
Treasury shares repurchased		6.3	4.5
Total value of stock repurchased in period, including unsettled shares		600,000
Payments for repurchase of common stock	$ 8,127	$ 591,873	$ 300,000