Restructuring (Restructuring Charges by Segment) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Restructuring Cost and Reserve [Line Items]
Restructuring	$ 12,061	$ 13,766	$ 62,142	$ 62,251
2014 Restructuring Program [Member] | Enterprise and Service Provider Division [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring	0	(263)	(177)	1,747
2014 Restructuring Program [Member] | GoTo Business Division [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring	0	0	0	50
2015 Restructuring Program [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring	7,600		14,600
2015 Restructuring Program [Member] | Enterprise and Service Provider Division [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring	7,625	13,714	14,716	59,580
2015 Restructuring Program [Member] | GoTo Business Division [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring	0	315	(79)	874
2015 Other Restructuring Program [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring	4,400		47,700
2015 Other Restructuring Program [Member] | Enterprise and Service Provider Division [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring	4,551	0	46,772	0
2015 Other Restructuring Program [Member] | GoTo Business Division [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring	$ (115)	$ 0	$ 910	$ 0