CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (UNAUDITED) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 249,815	$ 339,946
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustments, net of tax: 2017 - $5; 2016 - ($3,116)	66,459	41,583
Pension Plan and SERP liability adjustments, net of tax: 2017 - ($499); 2016 - ($380)	873	666
Comprehensive income	317,147	382,195
Less: comprehensive income attributable to non-controlling interests	(49,917)	(49,814)
Comprehensive income attributable to SNI	$ 267,230	$ 332,381