Loans, Allowance for Loan and Lease Losses, and Reserve for Off-Balance Sheet Credit Commitments (Details 8) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2012
Past Due Loans and Leases
30-59 Days Past Due	$ 36,384	$ 29,273
60-89 Days Past Due	603	10,813
Greater Than 90 Days and Accruing	1,688	981
Nonaccrual	83,275	99,787
Total Past Due and Nonaccrual Loans	121,950	140,854
Current	15,094,956	14,677,441
Total Loans and Leases	15,216,906	14,818,295	12,747,902
Commercial
Past Due Loans and Leases
30-59 Days Past Due	7,929	6,207
60-89 Days Past Due	347	4,219
Greater Than 90 Days and Accruing		602
Nonaccrual	7,292	9,087
Total Past Due and Nonaccrual Loans	15,568	20,115
Current	6,436,909	6,191,238
Total Loans and Leases	6,452,477	6,211,353
Commercial real estate mortgages
Past Due Loans and Leases
30-59 Days Past Due	16,960	16,968
60-89 Days Past Due		3,249
Nonaccrual	23,066	33,198
Total Past Due and Nonaccrual Loans	40,026	53,415
Current	2,897,431	2,776,279
Total Loans and Leases	2,937,457	2,829,694	2,213,114
Residential mortgage
Past Due Loans and Leases
60-89 Days Past Due	233	1,969
Greater Than 90 Days and Accruing	1,033	379
Nonaccrual	9,136	9,603
Total Past Due and Nonaccrual Loans	10,402	11,951
Current	4,017,339	3,950,254
Total Loans and Leases	4,027,741	3,962,205	3,805,807
Fixed
Past Due Loans and Leases
60-89 Days Past Due	233	1,969
Greater Than 90 Days and Accruing	1,033	379
Nonaccrual	4,579	4,902
Total Past Due and Nonaccrual Loans	5,845	7,250
Current	1,436,801	1,458,224
Total Loans and Leases	1,442,646	1,465,474
Variable
Past Due Loans and Leases
Nonaccrual	4,557	4,701
Total Past Due and Nonaccrual Loans	4,557	4,701
Current	2,580,538	2,492,030
Total Loans and Leases	2,585,095	2,496,731
Real estate construction
Past Due Loans and Leases
30-59 Days Past Due	3,537
60-89 Days Past Due		859
Nonaccrual	39,608	40,882
Total Past Due and Nonaccrual Loans	43,145	41,741
Current	203,969	181,039
Total Loans and Leases	247,114	222,780	313,409
Construction
Past Due Loans and Leases
Nonaccrual	14,602	15,067
Total Past Due and Nonaccrual Loans	14,602	15,067
Current	178,677	150,548
Total Loans and Leases	193,279	165,615
Land
Past Due Loans and Leases
30-59 Days Past Due	3,537
60-89 Days Past Due		859
Nonaccrual	25,006	25,815
Total Past Due and Nonaccrual Loans	28,543	26,674
Current	25,292	30,491
Total Loans and Leases	53,835	57,165
Home equity loans and lines of credit
Past Due Loans and Leases
30-59 Days Past Due	3,749	3,407
60-89 Days Past Due		480
Greater Than 90 Days and Accruing	630
Nonaccrual	4,103	6,424
Total Past Due and Nonaccrual Loans	8,482	10,311
Current	688,197	701,439
Total Loans and Leases	696,679	711,750	715,997
Installment loan
Past Due Loans and Leases
30-59 Days Past Due	138	58
60-89 Days Past Due	17	35
Nonaccrual	70	473
Total Past Due and Nonaccrual Loans	225	566
Current	137,320	142,227
Total Loans and Leases	137,545	142,793	125,793
Commercial Installment loan
Past Due Loans and Leases
Current	503	437
Total Loans and Leases	503	437
Consumer Installment loan
Past Due Loans and Leases
30-59 Days Past Due	138	58
60-89 Days Past Due	17	35
Nonaccrual	70	473
Total Past Due and Nonaccrual Loans	225	566
Current	136,817	141,790
Total Loans and Leases	137,042	142,356
Lease financing
Past Due Loans and Leases
30-59 Days Past Due	4,071	2,633
60-89 Days Past Due	6	2
Greater Than 90 Days and Accruing	25
Nonaccrual		120
Total Past Due and Nonaccrual Loans	4,102	2,755
Current	713,791	734,965
Total Loans and Leases	$ 717,893	$ 737,720