Earnings Per Share Information about Share Repurchase Plan (Details) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 20, 2017
Class of Stock [Line Items]
Stock Repurchased and Retired During Period, Shares	1,920	2,946	6,636	9,117
Stock Repurchased and Retired During Period, Value	$ 74,000	$ 90,001	$ 253,649	$ 291,674
Stock Repurchase Program, Remaining Authorized Repurchase Amount	$ 0		$ 0		$ 169,019
Stock Repurchase Program, Authorized Amount					$ 56,471
Shares Paid for Tax Withholding for Share Based Compensation		2	344	363
Adjustments Related to Tax Withholding for Share-based Compensation		$ 43	$ 13,074	$ 11,845
Weighted Average Number Diluted Shares Outstanding Adjustment	6,606	7,640	3,922	4,931
Shanda Asset Management Investment Limited [Member]
Class of Stock [Line Items]
Stock Repurchased and Retired During Period, Value			$ 225,490
Stock Repurchased During Period, Shares			5,568