Loans and leases and the allowance for credit losses (Details 4) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Impaired loans and leases
Recorded Investment	$ 1,096,554	$ 1,123,315
Unpaid Principal Balance	1,396,874	1,440,333
Related Allowance	158,134	168,001
Impaired Financing Receivable with No Related Allowance [Member]
Impaired loans and leases
Recorded Investment	330,650	398,590
Unpaid Principal Balance	410,224	505,602
Impaired Financing Receivable with Related Allowance [Member]
Impaired loans and leases
Recorded Investment	765,904	724,725
Unpaid Principal Balance	986,650	934,731
Related Allowance	158,134	168,001
Commercial, financial, leasing, etc. [Member]
Impaired loans and leases
Recorded Investment	162,684	171,642
Unpaid Principal Balance	195,962	206,288
Related Allowance	47,303	48,674
Commercial, financial, leasing, etc. [Member] | Impaired Financing Receivable with No Related Allowance [Member]
Impaired loans and leases
Recorded Investment	37,892	53,104
Unpaid Principal Balance	45,608	60,778
Commercial, financial, leasing, etc. [Member] | Impaired Financing Receivable with Related Allowance [Member]
Impaired loans and leases
Recorded Investment	124,792	118,538
Unpaid Principal Balance	150,354	145,510
Related Allowance	47,303	48,674
Commercial real estate loans [Member]
Impaired loans and leases
Recorded Investment	179,561	174,522
Unpaid Principal Balance	226,886	219,574
Related Allowance	19,854	17,651
Commercial real estate loans [Member] | Impaired Financing Receivable with No Related Allowance [Member]
Impaired loans and leases
Recorded Investment	65,961	71,636
Unpaid Principal Balance	83,706	91,118
Commercial real estate loans [Member] | Impaired Financing Receivable with Related Allowance [Member]
Impaired loans and leases
Recorded Investment	113,600	102,886
Unpaid Principal Balance	143,180	128,456
Related Allowance	19,854	17,651
Residential builder and developer [Member]
Impaired loans and leases
Recorded Investment	275,678	292,449
Unpaid Principal Balance	419,944	458,146
Related Allowance	44,597	52,562
Residential builder and developer [Member] | Impaired Financing Receivable with No Related Allowance [Member]
Impaired loans and leases
Recorded Investment	85,389	133,156
Unpaid Principal Balance	100,099	177,277
Residential builder and developer [Member] | Impaired Financing Receivable with Related Allowance [Member]
Impaired loans and leases
Recorded Investment	190,289	159,293
Unpaid Principal Balance	319,845	280,869
Related Allowance	44,597	52,562
Other commercial construction [Member]
Impaired loans and leases
Recorded Investment	102,510	106,886
Unpaid Principal Balance	110,906	114,501
Related Allowance	2,924	3,836
Other commercial construction [Member] | Impaired Financing Receivable with No Related Allowance [Member]
Impaired loans and leases
Recorded Investment	85,258	86,652
Unpaid Principal Balance	89,439	89,862
Other commercial construction [Member] | Impaired Financing Receivable with Related Allowance [Member]
Impaired loans and leases
Recorded Investment	17,252	20,234
Unpaid Principal Balance	21,467	24,639
Related Allowance	2,924	3,836
Residential real estate excluding Alt-A [Member]
Impaired loans and leases
Recorded Investment	126,377	121,568
Unpaid Principal Balance	151,593	145,123
Related Allowance	4,389	4,420
Residential real estate excluding Alt-A [Member] | Impaired Financing Receivable with No Related Allowance [Member]
Impaired loans and leases
Recorded Investment	18,840	19,686
Unpaid Principal Balance	25,511	25,625
Residential real estate excluding Alt-A [Member] | Impaired Financing Receivable with Related Allowance [Member]
Impaired loans and leases
Recorded Investment	107,537	101,882
Unpaid Principal Balance	126,082	119,498
Related Allowance	4,389	4,420
Residential Alt-A [Member]
Impaired loans and leases
Recorded Investment	177,436	184,752
Unpaid Principal Balance	218,018	223,920
Related Allowance	23,000	25,000
Residential Alt-A [Member] | Impaired Financing Receivable with No Related Allowance [Member]
Impaired loans and leases
Recorded Investment	37,310	34,356
Unpaid Principal Balance	65,861	60,942
Residential Alt-A [Member] | Impaired Financing Receivable with Related Allowance [Member]
Impaired loans and leases
Recorded Investment	140,126	150,396
Unpaid Principal Balance	152,157	162,978
Related Allowance	23,000	25,000
Home equity lines and loans [Member]
Impaired loans and leases
Recorded Investment	10,790	9,385
Unpaid Principal Balance	12,047	10,670
Related Allowance	2,709	2,306
Home equity lines and loans [Member] | Impaired Financing Receivable with Related Allowance [Member]
Impaired loans and leases
Recorded Investment	10,790	9,385
Unpaid Principal Balance	12,047	10,670
Related Allowance	2,709	2,306
Automobile [Member]
Impaired loans and leases
Recorded Investment	52,363	53,710
Unpaid Principal Balance	52,363	53,710
Related Allowance	10,983	11,468
Automobile [Member] | Impaired Financing Receivable with Related Allowance [Member]
Impaired loans and leases
Recorded Investment	52,363	53,710
Unpaid Principal Balance	52,363	53,710
Related Allowance	10,983	11,468
Other [Member]
Impaired loans and leases
Recorded Investment	9,155	8,401
Unpaid Principal Balance	9,155	8,401
Related Allowance	2,375	2,084
Other [Member] | Impaired Financing Receivable with Related Allowance [Member]
Impaired loans and leases
Recorded Investment	9,155	8,401
Unpaid Principal Balance	9,155	8,401
Related Allowance	$ 2,375	$ 2,084