Other Borrowed Funds and Subordinated Debentures (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Summary of other borrowed funds and subordinated debentures
Amount outstanding at December 31	$ 231,227	$ 280,226	$ 258,201
Weighted average rate at December 31	3.54%	2.85%	2.88%
Maximum amount outstanding at any month end	277,226	280,226	266,564
Daily average balance outstanding during the year	$ 217,542	$ 202,209	$ 201,273
Weighted average rate during the year	3.82%	3.85%	4.13%