Earnings Per Common Share - Additional Information (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012	Dec. 31, 2011
Disclosure Earning Per Share Additional Information [Abstract]
Options for aggregate common shares	339,863	232,000	339,863	232,000	232,000	197,000
Dilutive effect of stock options	15,440	6,174	13,834	3,925