Summarized Quarterly Financial Information (Unaudited) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Quarterly Financial Information Disclosure [Abstract]
Operating revenues	$ 851,753	$ 776,122	$ 732,102	$ 658,250	$ 669,152	$ 644,423	$ 708,132	$ 643,749	$ 3,018,227	$ 2,665,456	$ 2,530,809
Cost of services, excluding depreciation and amortization of intangible assets	322,973	270,150	195,087	199,147	200,478	207,099	190,181	181,138	987,357	778,896	699,294
Selling, general and administrative	210,849	193,645	178,498	202,187	206,895	167,361	198,666	191,877	785,179	764,799	729,055
Depreciation and amortization of intangible assets	41,277	41,291	26,438	28,590	31,498	31,617	34,173	31,294	137,596	128,582	117,580
Loss on disposal of property and equipment	1,563	40	44	2,516	(177)	(448)	1,647	(152)	4,163	870	1,681
Operating income	275,091	270,996	332,035	225,810	230,458	238,794	283,465	239,592	1,103,932	992,309	958,476
Interest expense, net	(27,806)	(50,439)	(16,835)	(12,967)	(15,789)	(12,235)	(12,232)	(12,431)	(108,047)	(52,687)	(48,710)
Equity in earnings of affiliates	11,289	23,392	27,290	18,945	18,521	17,586	27,263	22,261	80,916	85,631	79,644
Gain (loss) on derivatives	3,088	4,037	37,198	5,933	5,246	2,041	(1,339)	(3,137)	50,256	2,810	(7,085)
Miscellaneous, net	17,946	(9,543)	(13,194)	(402)	(4,519)	25	871	3,410	(5,193)	(212)	8,326
Provision for income taxes	76,706	75,110	120,326	71,249	55,868	75,910	92,359	76,906	343,391	301,043	307,623
Net income	202,902	163,333	246,168	166,070	178,049	170,301	205,669	172,789	778,473	726,808	683,028
Less: net income attributable to non-controlling interests	(38,194)	(38,774)	(52,450)	(42,227)	(46,203)	(38,962)	(51,875)	(44,493)	(171,645)	(181,533)	(177,958)
Net income attributable to SNI	$ 164,708	$ 124,559	$ 193,718	$ 123,843	$ 131,846	$ 131,339	$ 153,794	$ 128,296	$ 606,828	$ 545,275	$ 505,070
Basic net income per share:
Net income attributable to SNI common shareholders (in dollars per share)	$ 1.27	$ 0.96	$ 1.50	$ 0.94	$ 0.96	$ 0.93	$ 1.08	$ 0.88	$ 4.68	$ 3.86	$ 3.43
Diluted net income per share:
Net income attributable to SNI common shareholders (in dollars per share)	$ 1.27	$ 0.96	$ 1.49	$ 0.94	$ 0.96	$ 0.93	$ 1.07	$ 0.87	$ 4.66	$ 3.83	$ 3.40
Weighted average shares outstanding:
Basic (in shares)	129,211	129,177	129,225	131,259	136,876	140,738	142,342	146,322	129,665	141,297	147,326
Diluted (in shares)	129,728	129,704	129,868	131,942	137,708	141,628	143,224	147,440	130,255	142,193	148,502
Cash dividends per share of common stock (in dollars per share)	$ 0.23	$ 0.23	$ 0.23	$ 0.23	$ 0.20	$ 0.20	$ 0.20	$ 0.20	$ 0.92	$ 0.80