Loans and leases and the allowance for credit losses (Details 4) (USD $) In Thousands	Sep. 30, 2011	Dec. 31, 2010
Impaired loans and leases
Recorded Investment	$ 1,153,556	$ 1,175,670
Unpaid Principal Balance	1,377,891	1,370,544
Related Allowance	202,216	213,933
Commercial, financial, leasing, etc. [Member]
Impaired loans and leases
Recorded Investment	159,981	174,197
Unpaid Principal Balance	190,939	237,580
Related Allowance	41,474	40,909
Commercial, financial, leasing, etc. [Member] | Impaired Financing Receivable with No Related Allowance [Member]
Impaired loans and leases
Recorded Investment	55,175	52,453
Unpaid Principal Balance	66,315	66,692
Commercial, financial, leasing, etc. [Member] | Impaired Financing Receivable with Related Allowance [Member]
Impaired loans and leases
Recorded Investment	104,806	121,744
Unpaid Principal Balance	124,624	170,888
Related Allowance	41,474	40,909
Commercial real estate loans [Member]
Impaired loans and leases
Recorded Investment	186,642	188,244
Unpaid Principal Balance	231,921	221,815
Related Allowance	22,084	17,393
Commercial real estate loans [Member] | Impaired Financing Receivable with No Related Allowance [Member]
Impaired loans and leases
Recorded Investment	66,572	77,269
Unpaid Principal Balance	71,403	81,800
Commercial real estate loans [Member] | Impaired Financing Receivable with Related Allowance [Member]
Impaired loans and leases
Recorded Investment	120,070	110,975
Unpaid Principal Balance	160,518	140,015
Related Allowance	22,084	17,393
Residential builder and developer [Member]
Impaired loans and leases
Recorded Investment	336,047	334,707
Unpaid Principal Balance	416,331	381,070
Related Allowance	81,048	78,597
Residential builder and developer [Member] | Impaired Financing Receivable with No Related Allowance [Member]
Impaired loans and leases
Recorded Investment	146,743	71,162
Unpaid Principal Balance	174,243	86,039
Residential builder and developer [Member] | Impaired Financing Receivable with Related Allowance [Member]
Impaired loans and leases
Recorded Investment	189,304	263,545
Unpaid Principal Balance	242,088	295,031
Related Allowance	81,048	78,597
Other commercial construction [Member]
Impaired loans and leases
Recorded Investment	105,451	117,214
Unpaid Principal Balance	109,787	122,539
Related Allowance	13,182	22,067
Other commercial construction [Member] | Impaired Financing Receivable with No Related Allowance [Member]
Impaired loans and leases
Recorded Investment	18,490	36,280
Unpaid Principal Balance	18,734	37,107
Other commercial construction [Member] | Impaired Financing Receivable with Related Allowance [Member]
Impaired loans and leases
Recorded Investment	86,961	80,934
Unpaid Principal Balance	91,053	85,432
Related Allowance	13,182	22,067
Residential real estate excluding Alt-A [Member]
Impaired loans and leases
Recorded Investment	102,210	78,041
Unpaid Principal Balance	127,486	93,002
Related Allowance	2,247	3,375
Residential real estate excluding Alt-A [Member] | Impaired Financing Receivable with No Related Allowance [Member]
Impaired loans and leases
Recorded Investment	9,000	5,035
Unpaid Principal Balance	13,634	7,723
Residential real estate excluding Alt-A [Member] | Impaired Financing Receivable with Related Allowance [Member]
Impaired loans and leases
Recorded Investment	93,210	73,006
Unpaid Principal Balance	113,852	85,279
Related Allowance	2,247	3,375
Residential Alt-A [Member]
Impaired loans and leases
Recorded Investment	189,464	209,632
Unpaid Principal Balance	226,476	239,324
Related Allowance	26,000	36,000
Residential Alt-A [Member] | Impaired Financing Receivable with No Related Allowance [Member]
Impaired loans and leases
Recorded Investment	34,437	28,967
Unpaid Principal Balance	59,606	47,879
Residential Alt-A [Member] | Impaired Financing Receivable with Related Allowance [Member]
Impaired loans and leases
Recorded Investment	155,027	180,665
Unpaid Principal Balance	166,870	191,445
Related Allowance	26,000	36,000
Home equity lines and loans [Member]
Impaired loans and leases
Recorded Investment	11,730	11,799
Unpaid Principal Balance	12,920	13,378
Related Allowance	2,863	2,227
Home equity lines and loans [Member] | Impaired Financing Receivable with Related Allowance [Member]
Impaired loans and leases
Recorded Investment	11,730	11,799
Unpaid Principal Balance	12,920	13,378
Related Allowance	2,863	2,227
Automobile [Member]
Impaired loans and leases
Recorded Investment	54,748	58,858
Unpaid Principal Balance	54,748	58,858
Related Allowance	11,513	12,597
Automobile [Member] | Impaired Financing Receivable with Related Allowance [Member]
Impaired loans and leases
Recorded Investment	54,748	58,858
Unpaid Principal Balance	54,748	58,858
Related Allowance	11,513	12,597
Other [Member]
Impaired loans and leases
Recorded Investment	7,283	2,978
Unpaid Principal Balance	7,283	2,978
Related Allowance	1,805	768
Other [Member] | Impaired Financing Receivable with Related Allowance [Member]
Impaired loans and leases
Recorded Investment	7,283	2,978
Unpaid Principal Balance	7,283	2,978
Related Allowance	1,805	768
Impaired Financing Receivable with No Related Allowance [Member]
Impaired loans and leases
Recorded Investment	330,417	271,166
Unpaid Principal Balance	403,935	327,240
Impaired Financing Receivable with Related Allowance [Member]
Impaired loans and leases
Recorded Investment	823,139	904,504
Unpaid Principal Balance	973,956	1,043,304
Related Allowance	$ 202,216	$ 213,933