Loans Schedule of Recorded Investment in Impaired Loans (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Financing Receivable, Recorded Investment, Nonaccrual Status, Interest Income if Accrued	$ 1,061	$ 1,299	$ 2,182	$ 2,651
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	104,093		104,093		124,867
Recorded Investment With No Allowance	56,650		56,650		62,724
Recorded Investment With Allowance	37,752		37,752		47,848
Total Recorded Investment	94,402		94,402		110,572
Related Allowance	6,952		6,952		8,929
Impaired Financing Receivable, Average Recorded Investment and Cash Basis Method Interest Income
Average Recorded Investment	103,910	127,553	107,961	127,499
Income Recognized	300	318	555	1,127
Interest Income on Impaired Loans If Interest Had Been Accrued	1,301	1,577	2,412	2,912
Commercial real estate
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	52,690		52,690		64,780
Recorded Investment With No Allowance	24,961		24,961		29,216
Recorded Investment With Allowance	25,622		25,622		33,937
Total Recorded Investment	50,583		50,583		63,153
Related Allowance	3,566		3,566		5,210
Impaired Financing Receivable, Average Recorded Investment and Cash Basis Method Interest Income
Average Recorded Investment	57,588	67,605	60,870	67,192
Income Recognized	241	272	457	610
Land acquisition & development construction real estate
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	15,601		15,601		23,906
Recorded Investment With No Allowance	8,098		8,098		9,901
Recorded Investment With Allowance	3,869		3,869		7,226
Total Recorded Investment	11,967		11,967		17,127
Related Allowance	647		647		1,434
Impaired Financing Receivable, Average Recorded Investment and Cash Basis Method Interest Income
Average Recorded Investment	13,563	19,007	14,554	20,123
Income Recognized	11	15	22	456
Residential construction real estate
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	1,096		1,096		1,816
Recorded Investment With No Allowance	653		653		1,095
Recorded Investment With Allowance	0		0		277
Total Recorded Investment	653		653		1,372
Related Allowance	0		0		26
Impaired Financing Receivable, Average Recorded Investment and Cash Basis Method Interest Income
Average Recorded Investment	785	1,569	1,051	2,040
Income Recognized	0	0	0	0
Commercial construction real estate
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	2,749		2,749		397
Recorded Investment With No Allowance	269		269		279
Recorded Investment With Allowance	2,446		2,446		84
Total Recorded Investment	2,715		2,715		363
Related Allowance	908		908		85
Impaired Financing Receivable, Average Recorded Investment and Cash Basis Method Interest Income
Average Recorded Investment	1,471	6,346	918	7,118
Income Recognized	2	0	4	0
Total construction loans
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	19,446		19,446		26,119
Recorded Investment With No Allowance	9,020		9,020		11,275
Recorded Investment With Allowance	6,315		6,315		7,587
Total Recorded Investment	15,335		15,335		18,862
Related Allowance	1,555		1,555		1,545
Impaired Financing Receivable, Average Recorded Investment and Cash Basis Method Interest Income
Average Recorded Investment	15,819	26,922	16,523	29,281
Income Recognized	13	15	26	456
Residential real estate
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	7,222		7,222		9,448
Recorded Investment With No Allowance	4,885		4,885		5,081
Recorded Investment With Allowance	375		375		967
Total Recorded Investment	5,260		5,260		6,048
Related Allowance	301		301		249
Impaired Financing Receivable, Average Recorded Investment and Cash Basis Method Interest Income
Average Recorded Investment	5,852	8,311	5,969	9,429
Income Recognized	1	5	3	9
Agricultural real estate
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	9,191		9,191		8,895
Recorded Investment With No Allowance	6,656		6,656		6,429
Recorded Investment With Allowance	2,439		2,439		2,370
Total Recorded Investment	9,095		9,095		8,799
Related Allowance	133		133		335
Impaired Financing Receivable, Average Recorded Investment and Cash Basis Method Interest Income
Average Recorded Investment	9,747	8,255	9,830	6,611
Income Recognized	25	4	29	8
Total real estate loans
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	88,549		88,549		109,242
Recorded Investment With No Allowance	45,522		45,522		52,001
Recorded Investment With Allowance	34,751		34,751		44,861
Total Recorded Investment	80,273		80,273		96,862
Related Allowance	5,555		5,555		7,339
Impaired Financing Receivable, Average Recorded Investment and Cash Basis Method Interest Income
Average Recorded Investment	89,006	111,093	93,192	112,513
Income Recognized	280	296	515	1,083
Commercial
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	14,752		14,752		15,448
Recorded Investment With No Allowance	10,709		10,709		10,684
Recorded Investment With Allowance	2,679		2,679		2,901
Total Recorded Investment	13,388		13,388		13,585
Related Allowance	1,176		1,176		1,504
Impaired Financing Receivable, Average Recorded Investment and Cash Basis Method Interest Income
Average Recorded Investment	14,162	16,087	14,231	14,484
Income Recognized	14	18	28	36
Agricultural
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	792		792		177
Recorded Investment With No Allowance	419		419		39
Recorded Investment With Allowance	322		322		86
Total Recorded Investment	741		741		125
Related Allowance	221		221		86
Impaired Financing Receivable, Average Recorded Investment and Cash Basis Method Interest Income
Average Recorded Investment	742	373	538	502
Income Recognized	$ 6	$ 4	$ 12	$ 8