Loans, Allowance for Loan and Lease Losses, and Reserve for Off-Balance Sheet Credit Commitments (Details 8) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012	Jun. 30, 2012
Past Due Loans and Leases
30-59 Days Past Due	$ 5,005	$ 29,273
60-89 Days Past Due	15,415	10,813
Greater Than 90 Days and Accruing	643	981
Nonaccrual	76,673	99,787
Total Past Due and Nonaccrual Loans	97,736	140,854
Current	15,721,516	14,677,441
Total Loans and Leases	15,819,252	14,818,295	13,507,209
Commercial
Past Due Loans and Leases
30-59 Days Past Due	2,080	6,207
60-89 Days Past Due	10,565	4,219
Greater Than 90 Days and Accruing		602
Nonaccrual	11,654	9,087
Total Past Due and Nonaccrual Loans	24,299	20,115
Current	6,749,576	6,191,238
Total Loans and Leases	6,773,875	6,211,353
Commercial real estate mortgages
Past Due Loans and Leases
30-59 Days Past Due	2,523	16,968
60-89 Days Past Due	1,771	3,249
Nonaccrual	22,433	33,198
Total Past Due and Nonaccrual Loans	26,727	53,415
Current	3,074,442	2,776,279
Total Loans and Leases	3,101,169	2,829,694	2,424,333
Residential mortgage
Past Due Loans and Leases
60-89 Days Past Due	2,904	1,969
Greater Than 90 Days and Accruing	379	379
Nonaccrual	10,580	9,603
Total Past Due and Nonaccrual Loans	13,863	11,951
Current	4,139,188	3,950,254
Total Loans and Leases	4,153,051	3,962,205	3,822,630
Fixed
Past Due Loans and Leases
60-89 Days Past Due	508	1,969
Greater Than 90 Days and Accruing	379	379
Nonaccrual	4,402	4,902
Total Past Due and Nonaccrual Loans	5,289	7,250
Current	1,420,487	1,458,224
Total Loans and Leases	1,425,776	1,465,474
Variable
Past Due Loans and Leases
60-89 Days Past Due	2,396
Nonaccrual	6,178	4,701
Total Past Due and Nonaccrual Loans	8,574	4,701
Current	2,718,701	2,492,030
Total Loans and Leases	2,727,275	2,496,731
Real estate construction
Past Due Loans and Leases
60-89 Days Past Due		859
Nonaccrual	25,718	40,882
Total Past Due and Nonaccrual Loans	25,718	41,741
Current	192,090	181,039
Total Loans and Leases	217,808	222,780	301,829
Construction
Past Due Loans and Leases
Nonaccrual	11,553	15,067
Total Past Due and Nonaccrual Loans	11,553	15,067
Current	167,627	150,548
Total Loans and Leases	179,180	165,615
Land
Past Due Loans and Leases
60-89 Days Past Due		859
Nonaccrual	14,165	25,815
Total Past Due and Nonaccrual Loans	14,165	26,674
Current	24,463	30,491
Total Loans and Leases	38,628	57,165
Home equity loans and lines of credit
Past Due Loans and Leases
30-59 Days Past Due	100	3,407
60-89 Days Past Due		480
Greater Than 90 Days and Accruing	249
Nonaccrual	6,239	6,424
Total Past Due and Nonaccrual Loans	6,588	10,311
Current	694,093	701,439
Total Loans and Leases	700,681	711,750	741,270
Installment loan
Past Due Loans and Leases
30-59 Days Past Due	190	58
60-89 Days Past Due	24	35
Nonaccrual	24	473
Total Past Due and Nonaccrual Loans	238	566
Current	149,200	142,227
Total Loans and Leases	149,438	142,793	130,200
Commercial Installment loan
Past Due Loans and Leases
30-59 Days Past Due	2
Total Past Due and Nonaccrual Loans	2
Current	438	437
Total Loans and Leases	440	437
Consumer Installment loan
Past Due Loans and Leases
30-59 Days Past Due	188	58
60-89 Days Past Due	24	35
Nonaccrual	24	473
Total Past Due and Nonaccrual Loans	236	566
Current	148,762	141,790
Total Loans and Leases	148,998	142,356
Lease financing
Past Due Loans and Leases
30-59 Days Past Due	112	2,633
60-89 Days Past Due	151	2
Greater Than 90 Days and Accruing	15
Nonaccrual	25	120
Total Past Due and Nonaccrual Loans	303	2,755
Current	722,927	734,965
Total Loans and Leases	$ 723,230	$ 737,720