Employee Termination Programs - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Restructuring Cost And Reserve [Line Items]
Increase (decrease) in net income related to voluntary early retirement and termination costs		$ (3,600)	$ 200	$ (6,900)
Net income attributable to SNI	$ 184,608	193,718	475,505	317,561
Voluntary Early Retirement Program and Employee Termination [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring charges		$ 5,800	300	$ 11,200
Reorganization [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring charges			11,207
Net income attributable to SNI	(2,400)		(6,900)
Costs for severance, retention, relocation and benefit cost	$ 3,900		$ 11,200