Stock Repurchases (Details) (USD $) In Thousands, except Share data, unless otherwise specified	1 Months Ended	3 Months Ended			12 Months Ended
	Jun. 30, 2011	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Dec. 31, 2012
Stock Repurchases
Repurchase of common stock, authorized amount	$ 20,000
Repurchase of common stock, remaining authorized amount					12,467
Shares repurchased		147,600	286,109	27,803	0
Average price per share (in dollars per share)		$ 17.02	$ 16.08	$ 15.52
Average commissions per share (in dollars per share)		$ 0.03	$ 0.03	$ 0.03
Value of stock repurchased		$ 2,512	$ 4,600	$ 431
Shares held as treasury stock	27,803	0	55,370	27,803