Restricted Stock (Details) (USD $) In Thousands, except Share data, unless otherwise specified	1 Months Ended		6 Months Ended			12 Months Ended	0 Months Ended
	May 31, 2013	May 31, 2012	Jun. 30, 2013	Jun. 30, 2013 Restricted Stock Units (RSUs) [Member]	Jun. 30, 2013 Restricted Stock Units (RSUs) [Member] Class B [Member] Outside Director [Member]	Dec. 31, 2012 Restricted Stock Units (RSUs) [Member] Class B [Member] Outside Director [Member]	Feb. 04, 2013 Restricted Stock Units (RSUs) [Member] Class B [Member] Executives [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares distribution period from grant date			1 year
Total value of shares issued					$ 440	$ 440	$ 1,241
Shares issued (in shares)							52,389
Value of each share issued (in dollars per share)	$ 24.30	$ 21.87					$ 23.69
Summary of stock Issuances [Abstract]
Shares granted (in shares)	18,106	20,119
Vesting Date	May 07, 2014	May 08, 2013
Service Period	7/1/2013 - 6/30/2014	7/1/2012 - 6/30/2013
Period restricted stocks will vest ratably from date of grant				3 years