Stockholders Equity (Details Textual) (USD $)	12 Months Ended				12 Months Ended				12 Months Ended				12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2012 Stock Options [Member]	Dec. 31, 2012 Stock Option Plan [Member]	Dec. 31, 2011 Stock Option Plan [Member]	Dec. 31, 2010 Stock Option Plan [Member]	Dec. 31, 2012 Common Class A [Member]	Dec. 31, 2011 Common Class A [Member]	Dec. 31, 2010 Common Class A [Member]	Dec. 30, 2005 Common Class A [Member]	Dec. 31, 2012 Common Class A [Member] Maximum [Member]	Dec. 31, 2011 Common Class A [Member] Maximum [Member]	Dec. 31, 2012 Common Class A [Member] Minimum [Member]
Stockholders' Equity (Textual) [Abstract]
Dividend per share percent															200.00%
Stock repurchase program, number of additional shares authorized to be repurchased									300,000	300,000
Stock repurchase program, number of shares authorized to be repurchased, Percent													9.00%	9.00%
Share Based compensation Number of share authorized					150,000				150,000
Share based compensation of option price based on fair value					85.00%
Number of outstanding options	23,350	36,062	38,712	68,637		23,350
Exercise prices of shares outstanding, minimum									$ 15.063	$ 15.063	$ 15.063
Exercise prices of shares outstanding, maximum									$ 31.83	$ 31.83	$ 31.83
Weighted average remaining contractual life									2 years	2 years	3 years
Weighted average intrinsic value of options exercised						$ 8.13
Options to purchase an aggregate of shares	23,350	36,062	38,712						23,350			23,950
Options outstanding exercise prices	$ 31.17	$ 28.90	$ 28.36	$ 26.09
Weighted average intrinsic value of options exercised	$ 24.82	$ 21.44	$ 15.06
Aggregate value of weighted average intrinsic value of options exercised						$ 99,714
Aggregate value of weighted average intrinsic value of options exercisable						$ 41,549	$ 49,145	$ 41,895
Number of shares repurchase during the period Under Stock repurchase plan									8,110
Sock option exercisable period					10 years