Federal and state income taxes Reconciliation of Unrecognized Tax Benefits (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Income Tax Disclosure [Abstract]
Unrecognized Tax Benefits, Beginning of Year	$ 5,017	$ 4,914
Unrecognized Tax Benefits, Increases Resulting from Current Period Tax Positions	345	551
Unrecognized Tax Benefits, Decreases Resulting from Current Period Tax Positions	(694)	0
Unrecognized Tax Benefits, Increases Resulting from Prior Period Tax Positions	149	143
Unrecognized Tax Benefits, Decreases Resulting from Prior Period Tax Positions	(67)	(34)
Unrecognized Tax Benefits, Reductions Resulting from Lapse of Applicable Statute of Limitations	(498)	(557)
Unrecognized Tax Benefits, End of Year	$ 4,252	$ 5,017