Loans - Schedule of Recorded Investment in Impaired Loans (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	$ 124,867	$ 158,512	$ 264,801
Recorded Investment With No Allowance	62,724	82,232	117,004
Recorded Investment With Allowance	47,848	53,953	113,592
Total Recorded Investment	110,572	136,185	230,596
Related allowance	8,929	10,297	32,838
Commercial real estate
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	64,780	84,300	97,745
Recorded Investment With No Allowance	29,216	39,049	62,769
Recorded Investment With Allowance	33,937	34,774	23,218
Total Recorded Investment	63,153	73,823	85,987
Related allowance	5,210	4,112	6,741
Land acquisition & development construction real estate
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	23,906	28,558	73,258
Recorded Investment With No Allowance	9,901	15,891	22,300
Recorded Investment With Allowance	7,226	7,173	39,131
Total Recorded Investment	17,127	23,064	61,431
Related allowance	1,434	1,457	12,084
Residential construction real estate
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	1,816	3,018	13,721
Recorded Investment With No Allowance	1,095	1,976	10,427
Recorded Investment With Allowance	277	710	2,044
Total Recorded Investment	1,372	2,686	12,471
Related allowance	26	251	312
Commercial construction real estate
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	397	10,447	26,647
Recorded Investment With No Allowance	279	7,785	3,510
Recorded Investment With Allowance	84	340	21,026
Total Recorded Investment	363	8,125	24,536
Related allowance	85	69	5,042
Total construction loans
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	26,119	42,023	113,626
Recorded Investment With No Allowance	11,275	25,652	36,237
Recorded Investment With Allowance	7,587	8,223	62,201
Total Recorded Investment	18,862	33,875	98,438
Related allowance	1,545	1,777	17,438
Residential real estate
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	9,448	13,271	18,305
Recorded Investment With No Allowance	5,081	6,152	2,678
Recorded Investment With Allowance	967	4,495	15,626
Total Recorded Investment	6,048	10,647	18,304
Related allowance	249	1,677	3,844
Agricultural real estate
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	8,895	5,559	8,018
Recorded Investment With No Allowance	6,429	1,834	7,470
Recorded Investment With Allowance	2,370	3,227	0
Total Recorded Investment	8,799	5,061	7,470
Related allowance	335	784	0
Total real estate loans
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	109,242	145,153	237,694
Recorded Investment With No Allowance	52,001	72,687	109,154
Recorded Investment With Allowance	44,861	50,719	101,045
Total Recorded Investment	96,862	123,406	210,199
Related allowance	7,339	8,350	28,023
Commercial
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	15,448	12,770	26,348
Recorded Investment With No Allowance	10,684	9,036	7,354
Recorded Investment With Allowance	2,901	3,206	12,284
Total Recorded Investment	13,585	12,242	19,638
Related allowance	1,504	1,919	4,664
Agricultural
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	177	589	759
Recorded Investment With No Allowance	39	509	496
Recorded Investment With Allowance	86	28	263
Total Recorded Investment	125	537	759
Related allowance	$ 86	$ 28	$ 151