Loans and Allowance for Loan Losses (Credit Quality of Commercial Loan Portfolio) (Details) (USD $) In Thousands	Jun. 30, 2011	Dec. 31, 2010
Total	$ 5,452,711	$ 5,483,733
Pass [Member]
Total	5,006,675	5,006,500
Pass [Member] | Business [Member]
Total	2,768,123	2,801,328
Pass [Member] | Real Estate - Construction and Land [Member]
Total	334,465	327,167
Pass [Member] | Real Estate - Business [Member]
Total	1,904,087	1,878,005
Special Mention [Member]
Total	110,291	174,014
Special Mention [Member] | Business [Member]
Total	50,266	67,142
Special Mention [Member] | Real Estate - Construction and Land [Member]
Total	9,751	29,345
Special Mention [Member] | Real Estate - Business [Member]
Total	50,274	77,527
Substandard [Member]
Total	264,226	225,292
Substandard [Member] | Business [Member]
Total	77,137	79,640
Substandard [Member] | Real Estate - Construction and Land [Member]
Total	60,539	51,589
Substandard [Member] | Real Estate - Business [Member]
Total	126,550	94,063
Non-accrual [Member]
Total	71,519	77,927
Non-accrual [Member] | Business [Member]
Total	26,030	8,933
Non-accrual [Member] | Real Estate - Construction and Land [Member]
Total	28,709	52,752
Non-accrual [Member] | Real Estate - Business [Member]
Total	16,780	16,242
Business [Member]
Total	2,921,556	2,957,043
Real Estate - Construction and Land [Member]
Total	433,464	460,853
Real Estate - Business [Member]
Total	$ 2,097,691	$ 2,065,837