Loans Schedule of Recorded Investment in Impaired Loans (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011	Dec. 31, 2011
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	$ 187,688		$ 187,688		$ 264,801
Recorded Investment With No Allowance	101,004		101,004		117,004
Recorded Investment With Allowance	61,496		61,496		113,592
Total Recorded Investment	162,500		162,500		230,596
Related Allowance	17,943		17,943		32,838
Impaired Financing Receivable, Average Recorded Investment and Cash Basis Method Interest Income
Average Recorded Investment	200,803	242,072	217,702	224,340
Income Recognized	395	330	829	530
Interest Income on Impaired Loans If Interest Had Been Accrued	580	762	1,263	1,454
Commercial real estate
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	88,616		88,616		97,745
Recorded Investment With No Allowance	60,518		60,518		62,769
Recorded Investment With Allowance	19,509		19,509		23,218
Total Recorded Investment	80,027		80,027		85,987
Related Allowance	5,388		5,388		6,741
Impaired Financing Receivable, Average Recorded Investment and Cash Basis Method Interest Income
Average Recorded Investment	87,135	90,625	85,701	81,429
Income Recognized	320	110	671	202
Land acquisition & development construction real estate
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	50,837		50,837		73,258
Recorded Investment With No Allowance	21,910		21,910		22,300
Recorded Investment With Allowance	16,667		16,667		39,131
Total Recorded Investment	38,577		38,577		61,431
Related Allowance	6,776		6,776		12,084
Impaired Financing Receivable, Average Recorded Investment and Cash Basis Method Interest Income
Average Recorded Investment	51,949	54,500	56,924	49,444
Income Recognized	30	42	46	87
Residential construction real estate
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	3,505		3,505		13,721
Recorded Investment With No Allowance	1,541		1,541		10,427
Recorded Investment With Allowance	1,632		1,632		2,044
Total Recorded Investment	3,173		3,173		12,471
Related Allowance	276		276		312
Impaired Financing Receivable, Average Recorded Investment and Cash Basis Method Interest Income
Average Recorded Investment	3,637	18,841	8,810	17,697
Income Recognized	0	18	0	37
Commercial construction real estate
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	13,743		13,743		26,647
Recorded Investment With No Allowance	1,558		1,558		3,510
Recorded Investment With Allowance	9,463		9,463		21,026
Total Recorded Investment	11,021		11,021		24,536
Related Allowance	572		572		5,042
Impaired Financing Receivable, Average Recorded Investment and Cash Basis Method Interest Income
Average Recorded Investment	20,807	18,306	22,536	18,811
Income Recognized	0	0	0	0
Total construction loans
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	68,085		68,085		113,626
Recorded Investment With No Allowance	25,009		25,009		36,237
Recorded Investment With Allowance	27,762		27,762		62,201
Total Recorded Investment	52,771		52,771		98,438
Related Allowance	7,624		7,624		17,438
Impaired Financing Receivable, Average Recorded Investment and Cash Basis Method Interest Income
Average Recorded Investment	76,393	91,647	88,270	85,952
Income Recognized	30	60	46	124
Residential real estate
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	12,176		12,176		18,305
Recorded Investment With No Allowance	4,332		4,332		2,678
Recorded Investment With Allowance	7,661		7,661		15,626
Total Recorded Investment	11,993		11,993		18,304
Related Allowance	2,111		2,111		3,844
Impaired Financing Receivable, Average Recorded Investment and Cash Basis Method Interest Income
Average Recorded Investment	14,726	23,085	16,251	19,415
Income Recognized	12	97	21	97
Agricultural real estate
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	5,733		5,733		8,018
Recorded Investment With No Allowance	3,302		3,302		7,470
Recorded Investment With Allowance	1,933		1,933		0
Total Recorded Investment	5,235		5,235		7,470
Related Allowance	76		76		0
Impaired Financing Receivable, Average Recorded Investment and Cash Basis Method Interest Income
Average Recorded Investment	6,816	6,086	10,039	5,094
Income Recognized	0	40	32	42
Total real estate loans
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	174,610		174,610		237,694
Recorded Investment With No Allowance	93,161		93,161		109,154
Recorded Investment With Allowance	56,865		56,865		101,045
Total Recorded Investment	150,026		150,026		210,199
Related Allowance	15,199		15,199		28,023
Impaired Financing Receivable, Average Recorded Investment and Cash Basis Method Interest Income
Average Recorded Investment	185,070	211,443	200,261	191,890
Income Recognized	362	307	770	465
Commercial
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	12,526		12,526		26,348
Recorded Investment With No Allowance	7,748		7,748		7,354
Recorded Investment With Allowance	4,226		4,226		12,284
Total Recorded Investment	11,974		11,974		19,638
Related Allowance	2,339		2,339		4,664
Impaired Financing Receivable, Average Recorded Investment and Cash Basis Method Interest Income
Average Recorded Investment	14,355	29,626	16,195	31,505
Income Recognized	22	23	44	65
Agricultural
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	552		552		759
Recorded Investment With No Allowance	95		95		496
Recorded Investment With Allowance	405		405		263
Total Recorded Investment	500		500		759
Related Allowance	405		405		151
Impaired Financing Receivable, Average Recorded Investment and Cash Basis Method Interest Income
Average Recorded Investment	1,378	1,003	1,246	945
Income Recognized	$ 11	$ 0	$ 15	$ 0