Employee Benefit Plans, Share Based Compensation (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Stock Based Compensation Expense Recorded in Cost and Expense Categories
Share-Based Compensation Expense	$ 187.5	$ 226.8	$ 217.3
Stock Options
Stock Based Compensation Expense Recorded in Cost and Expense Categories
Share-Based Compensation Expense	0.5	4.4	6.6
RSUs, RSAs, and PSAs
Stock Based Compensation Expense Recorded in Cost and Expense Categories
Share-Based Compensation Expense	171.3	206.9	197.3
Employee Stock Purchase Plan
Stock Based Compensation Expense Recorded in Cost and Expense Categories
Share-Based Compensation Expense	15.7	15.5	13.4
Cost of Revenues, Product
Stock Based Compensation Expense Recorded in Cost and Expense Categories
Share-Based Compensation Expense	4.6	6.4	5.6
Cost of Revenues, Service
Stock Based Compensation Expense Recorded in Cost and Expense Categories
Share-Based Compensation Expense	17.5	15.3	13.8
Research and Development Expense
Stock Based Compensation Expense Recorded in Cost and Expense Categories
Share-Based Compensation Expense	86.6	126.5	125.4
Selling and Marketing Expense
Stock Based Compensation Expense Recorded in Cost and Expense Categories
Share-Based Compensation Expense	55.6	55.2	45.6
General and Administrative Expense
Stock Based Compensation Expense Recorded in Cost and Expense Categories
Share-Based Compensation Expense	$ 23.2	$ 23.4	$ 26.9