Equity Incentive Plans, Share-based Payment Award (Details) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested [Roll Forward]
RSU nonvested shares beginning balance	6,009,831	5,492,220	5,241,306
RSU shares granted	1,616,632	1,976,583	1,627,191
RSU shares assumed upon acquisition		523,043
RSU shares forfeited/expired	(282,964)	(370,196)	(184,926)
RSU shares vested	(1,813,465)	(1,611,819)	(1,191,351)
RSU nonvested shares ending balance	5,530,034	6,009,831	5,492,220
Closing price of company's common stock related to calculation of aggregate intrinsic value of stock options (in dollars per share)	$ 47.76
Restricted stock units' weighted average remaining expense recognition period (in years)	2 years 0 months 4 days
Restricted stock units [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested [Roll Forward]
Total intrinsic value of RSU's vested during the period	$ 74.6	$ 54.4	$ 43.7
Total intrinsic value of RSU's outstanding	$ 264.1
Restricted stock units' weighted average remaining expense recognition period (in years)	2 years 0 months 26 days
Weighted average fair values per share of restricted stock units awarded (amount per share)	$ 34.24	$ 29.92	$ 30.48