Stock-Based Compensation (Schedule of Restricted Stock Awards) (Details) (USD $)	0 Months Ended	12 Months Ended
	May 15, 2011	Dec. 31, 2012 Grant Date - 3/3/2010 [Member] Restricted Stock [Member]	Dec. 31, 2012 Grant Date - 5/28/2010 [Member] Restricted Stock [Member]	Dec. 31, 2012 Grant Date - 5/28/2010 (2) [Member] Restricted Stock [Member]	Dec. 31, 2012 Grant Date - 10/21/2010 [Member] Restricted Stock [Member]	Dec. 31, 2012 Grant Date - 3/15/2011 [Member] Restricted Stock [Member]	Dec. 31, 2012 Grant Date - 7/21/2011 [Member] Restricted Stock [Member]	Dec. 31, 2012 Grant Date - 8/29/2011 [Member] Restricted Stock [Member]	Dec. 31, 2012 Grant Date - 2/1/2012 [Member] Restricted Stock [Member]	Dec. 31, 2012 Grant Date - 3/6/2012 [Member] Restricted Stock [Member]	Dec. 31, 2012 Grant Date - 5/23/2012 [Member] Restricted Stock [Member]	Dec. 31, 2012 Grant Date - 12/11/2012 [Member] Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grant Date		March 3, 2010	May 28, 2010	May 28, 2010	October 21, 2010	March 15, 2011	July 21, 2011	August 29, 2011	February 1, 2012	March 6, 2012	May 23, 2012	December 11, 2012
Shares		12,185	2,500	17,500	7,500	24,836	16,600	5,000	66,000	18,347	8,000	16,330
Grant Date Fair Value	$ 38.46	$ 31.92	$ 28.07	$ 28.07	$ 31.04	$ 38.46	$ 38.44	$ 24.50	$ 30.15	$ 27.49	$ 28.05	$ 41.98
Aggregate Fair Value		$ 389,000	$ 70,000	$ 491,000	$ 233,000	$ 955,000	$ 638,000	$ 123,000	$ 1,990,000	$ 504,000	$ 224,000	$ 686,000
Vesting Date		March 3, 2014	February 28, 2012	May 28, 2014	October 21, 2014	March 15, 2015	July 21, 2015	August 29, 2014	February 1, 2016	March 6, 2016	May 23, 2016	December 12, 2015