Loans Schedule of Recorded Investment in Impaired Loans (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	$ 180,623		$ 180,623		$ 264,801
Recorded Investment With No Allowance	101,184		101,184		117,004
Recorded Investment With Allowance	53,274		53,274		113,592
Total Recorded Investment	154,458		154,458		230,596
Related Allowance	14,684		14,684		32,838
Impaired Financing Receivable, Average Recorded Investment and Cash Basis Method Interest Income
Average Recorded Investment	165,816	259,070	198,334	234,644
Income Recognized	431	456	1,260	986
Interest Income on Impaired Loans If Interest Had Been Accrued	452	812	1,688	2,263
Commercial real estate
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	88,185		88,185		97,745
Recorded Investment With No Allowance	61,509		61,509		62,769
Recorded Investment With Allowance	17,143		17,143		23,218
Total Recorded Investment	78,652		78,652		85,987
Related Allowance	4,453		4,453		6,741
Impaired Financing Receivable, Average Recorded Investment and Cash Basis Method Interest Income
Average Recorded Investment	81,313	86,347	82,689	83,479
Income Recognized	366	188	1,037	390
Land acquisition & development construction real estate
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	43,595		43,595		73,258
Recorded Investment With No Allowance	19,660		19,660		22,300
Recorded Investment With Allowance	12,558		12,558		39,131
Total Recorded Investment	32,218		32,218		61,431
Related Allowance	4,137		4,137		12,084
Impaired Financing Receivable, Average Recorded Investment and Cash Basis Method Interest Income
Average Recorded Investment	36,206	66,470	49,528	54,494
Income Recognized	30	3	76	90
Residential construction real estate
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	3,333		3,333		13,721
Recorded Investment With No Allowance	1,257		1,257		10,427
Recorded Investment With Allowance	1,744		1,744		2,044
Total Recorded Investment	3,001		3,001		12,471
Related Allowance	276		276		312
Impaired Financing Receivable, Average Recorded Investment and Cash Basis Method Interest Income
Average Recorded Investment	3,151	17,627	8,591	17,248
Income Recognized	0	18	0	55
Commercial construction real estate
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	13,071		13,071		26,647
Recorded Investment With No Allowance	1,379		1,379		3,510
Recorded Investment With Allowance	9,140		9,140		21,026
Total Recorded Investment	10,519		10,519		24,536
Related Allowance	588		588		5,042
Impaired Financing Receivable, Average Recorded Investment and Cash Basis Method Interest Income
Average Recorded Investment	10,817	23,441	18,601	20,371
Income Recognized	0	0	0	0
Total construction loans
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	59,999		59,999		113,626
Recorded Investment With No Allowance	22,296		22,296		36,237
Recorded Investment With Allowance	23,442		23,442		62,201
Total Recorded Investment	45,738		45,738		98,438
Related Allowance	5,001		5,001		17,438
Impaired Financing Receivable, Average Recorded Investment and Cash Basis Method Interest Income
Average Recorded Investment	50,174	107,538	76,720	92,113
Income Recognized	30	21	76	145
Residential real estate
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	12,044		12,044		18,305
Recorded Investment With No Allowance	5,570		5,570		2,678
Recorded Investment With Allowance	5,070		5,070		15,626
Total Recorded Investment	10,640		10,640		18,304
Related Allowance	1,736		1,736		3,844
Impaired Financing Receivable, Average Recorded Investment and Cash Basis Method Interest Income
Average Recorded Investment	12,416	22,972	14,667	19,101
Income Recognized	1	160	22	257
Agricultural real estate
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	5,929		5,929		8,018
Recorded Investment With No Allowance	3,293		3,293		7,470
Recorded Investment With Allowance	2,137		2,137		0
Total Recorded Investment	5,430		5,430		7,470
Related Allowance	158		158		0
Impaired Financing Receivable, Average Recorded Investment and Cash Basis Method Interest Income
Average Recorded Investment	5,173	7,694	7,090	6,392
Income Recognized	9	56	41	98
Total real estate loans
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	166,157		166,157		237,694
Recorded Investment With No Allowance	92,668		92,668		109,154
Recorded Investment With Allowance	47,792		47,792		101,045
Total Recorded Investment	140,460		140,460		210,199
Related Allowance	11,348		11,348		28,023
Impaired Financing Receivable, Average Recorded Investment and Cash Basis Method Interest Income
Average Recorded Investment	149,076	224,551	181,166	201,085
Income Recognized	406	425	1,176	890
Commercial
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	13,824		13,824		26,348
Recorded Investment With No Allowance	8,338		8,338		7,354
Recorded Investment With Allowance	5,070		5,070		12,284
Total Recorded Investment	13,408		13,408		19,638
Related Allowance	2,924		2,924		4,664
Impaired Financing Receivable, Average Recorded Investment and Cash Basis Method Interest Income
Average Recorded Investment	15,992	33,634	16,129	32,634
Income Recognized	21	31	65	96
Agricultural
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	642		642		759
Recorded Investment With No Allowance	178		178		496
Recorded Investment With Allowance	412		412		263
Total Recorded Investment	590		590		759
Related Allowance	412		412		151
Impaired Financing Receivable, Average Recorded Investment and Cash Basis Method Interest Income
Average Recorded Investment	748	885	1,039	925
Income Recognized	$ 4	$ 0	$ 19	$ 0