Summary of Significant Accounting Policies (Details Textual) (USD $)	0 Months Ended	3 Months Ended								12 Months Ended				12 Months Ended	1 Months Ended	12 Months Ended
	Oct. 02, 2012	Dec. 31, 2012 Markets Networks	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012 Markets Networks	Dec. 31, 2011	Dec. 31, 2010	Mar. 31, 2013 Subsequent Event [Member]	Dec. 31, 2012 Common Class [Member]	Mar. 31, 2013 Common Class [Member] Subsequent Event [Member]	Dec. 31, 2012 Favorable Lease Agreements [Member] Maximum [Member]	Dec. 31, 2012 Favorable Lease Agreements [Member] Minimum [Member]	Dec. 31, 2012 Other Intangible Assets [Member] Maximum [Member]	Dec. 31, 2012 Other Intangible Assets [Member] Minimum [Member]
Summary Of Significant Accounting Policies [Line Items]
Number of stock options outstanding having antidilutive effect										93,000	304,000	392,000
Four-for-three stock split										The stock split increased the Company's issued and outstanding shares of common stock from approximately 3,659,753 shares of Class A Common Stock and 597,504 shares of Class B Common Stock to approximately 4,877,323 and 796,672 shares, respectively.
Concentration Risk, Market Risk										44.00%	44.00%	45.00%
Depreciation expense										$ 6,805,000	$ 7,053,000	$ 7,285,000
Interest expense related to the amortization of debt issuance costs										231,000	642,000	1,079,000
Write-off debt issuance costs		0	0	0	0	0	0	1,326,000	0	0	1,326,000	0
Net book value of deferred costs		793,000				1,024,000				793,000	1,024,000
Share repurchase program, authorized amount														60,000,000
Treasury Stock, Shares Acquired										2,924,000	5,380,000	7,288,000
Treasury Stock Acquired, Average Cost Per Share										$ 27.30	$ 21.71	$ 10.69
Advertising and promotion costs										3,182,000	3,675,000	3,562,000
Stock repurchase program, remaining authorization amount														14,200,000	30,000,000
Special cash dividend declared on Classes A and B Common Stock	$ 1.24									$ 1.24	$ 0	$ 0
Dividend paid	$ 7,000,000
Amortized over the lives of the leases term range																26 years	4 years	11 years	1 year
Number of shares authorized to be repurchased		60,000,000								60,000,000			75,800,000
Number of broadcast licenses		97								97
Number of market serving		25								25