Earnings Per Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Earnings Per Share [Abstract]
Net income	$ 17,692	$ 13,824	$ 49,764	$ 41,125
Weighted average shares outstanding (in shares)	5,111,201	5,109,717	5,110,435	5,108,832
Net income per common share- basic and diluted (in dollars per share)	$ 3.46	$ 2.71	$ 9.74	$ 8.05