Loans - Schedule of Average Recorded Investment in and Income Recognized on Impaired Loans (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Schedule of Average Recorded Investment in and Income Recognized on Impaired Loans
Average Recorded Investment	$ 185,281	$ 238,175	$ 156,384
Income Recognized	1,631	1,659
Impaired Financing Receivable, Average Recorded Investment and Cash Basis Method Interest Income
Interest income on impaired loans if interest had been accrued	8,463	12,358	8,824
Commercial real estate
Schedule of Average Recorded Investment in and Income Recognized on Impaired Loans
Average Recorded Investment	78,670	85,702	49,713
Income Recognized	1,339	633
Land acquisition & development construction real estate
Schedule of Average Recorded Investment in and Income Recognized on Impaired Loans
Average Recorded Investment	44,457	57,675	34,871
Income Recognized	110	96
Residential construction real estate
Schedule of Average Recorded Investment in and Income Recognized on Impaired Loans
Average Recorded Investment	8,431	19,769	15,097
Income Recognized	4	384
Commercial construction real estate
Schedule of Average Recorded Investment in and Income Recognized on Impaired Loans
Average Recorded Investment	16,401	20,676	21,086
Income Recognized	0	0
Total construction loans
Schedule of Average Recorded Investment in and Income Recognized on Impaired Loans
Average Recorded Investment	69,289	98,120	71,054
Income Recognized	114	480
Residential real estate
Schedule of Average Recorded Investment in and Income Recognized on Impaired Loans
Average Recorded Investment	13,703	15,768	10,889
Income Recognized	26	258
Agricultural real estate
Schedule of Average Recorded Investment in and Income Recognized on Impaired Loans
Average Recorded Investment	6,936	6,188	1,737
Income Recognized	41	167
Total real estate loans
Schedule of Average Recorded Investment in and Income Recognized on Impaired Loans
Average Recorded Investment	168,598	205,778	133,393
Income Recognized	1,520	1,538
Commercial
Schedule of Average Recorded Investment in and Income Recognized on Impaired Loans
Average Recorded Investment	15,741	31,490	22,017
Income Recognized	84	121
Agricultural
Schedule of Average Recorded Investment in and Income Recognized on Impaired Loans
Average Recorded Investment	942	907	974
Income Recognized	$ 27	$ 0