Loans and leases and the allowance for credit losses (Details 4) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Impaired loans and leases
Recorded Investment	$ 1,043,996	$ 1,123,315
Unpaid Principal Balance	1,331,869	1,440,333
Related Allowance	154,396	168,001
Impaired Financing Receivable With Recorded Allowance [Member]
Impaired loans and leases
Recorded Investment	770,780	724,725
Unpaid Principal Balance	974,217	934,731
Related Allowance	154,396	168,001
Impaired Financing Receivable with No Related Allowance [Member]
Impaired loans and leases
Recorded Investment	273,216	398,590
Unpaid Principal Balance	357,652	505,602
Related Allowance
Commercial, financial, leasing [Member]
Impaired loans and leases
Recorded Investment	161,849	171,642
Unpaid Principal Balance	191,950	206,288
Related Allowance	39,134	48,674
Commercial, financial, leasing [Member] | Impaired Financing Receivable With Recorded Allowance [Member]
Impaired loans and leases
Recorded Investment	118,670	118,538
Unpaid Principal Balance	139,477	145,510
Related Allowance	39,134	48,674
Commercial, financial, leasing [Member] | Impaired Financing Receivable with No Related Allowance [Member]
Impaired loans and leases
Recorded Investment	43,179	53,104
Unpaid Principal Balance	52,473	60,778
Related Allowance
Commercial real estate loans [Member]
Impaired loans and leases
Recorded Investment	179,294	174,522
Unpaid Principal Balance	227,836	219,574
Related Allowance	19,323	17,651
Commercial real estate loans [Member] | Impaired Financing Receivable With Recorded Allowance [Member]
Impaired loans and leases
Recorded Investment	116,765	102,886
Unpaid Principal Balance	148,232	128,456
Related Allowance	19,323	17,651
Commercial real estate loans [Member] | Impaired Financing Receivable with No Related Allowance [Member]
Impaired loans and leases
Recorded Investment	62,529	71,636
Unpaid Principal Balance	79,604	91,118
Related Allowance
Residential builder and developer [Member]
Impaired loans and leases
Recorded Investment	246,126	292,449
Unpaid Principal Balance	372,543	458,146
Related Allowance	33,490	52,562
Residential builder and developer [Member] | Impaired Financing Receivable With Recorded Allowance [Member]
Impaired loans and leases
Recorded Investment	135,172	159,293
Unpaid Principal Balance	243,663	280,869
Related Allowance	33,490	52,562
Residential builder and developer [Member] | Impaired Financing Receivable with No Related Allowance [Member]
Impaired loans and leases
Recorded Investment	110,954	133,156
Unpaid Principal Balance	128,880	177,277
Related Allowance
Other commercial construction [Member]
Impaired loans and leases
Recorded Investment	86,053	106,886
Unpaid Principal Balance	98,796	114,501
Related Allowance	12,404	3,836
Other commercial construction [Member] | Impaired Financing Receivable With Recorded Allowance [Member]
Impaired loans and leases
Recorded Investment	81,077	20,234
Unpaid Principal Balance	89,410	24,639
Related Allowance	12,404	3,836
Other commercial construction [Member] | Impaired Financing Receivable with No Related Allowance [Member]
Impaired loans and leases
Recorded Investment	4,976	86,652
Unpaid Principal Balance	9,386	89,862
Related Allowance
Residential real estate excluding Alt-A [Member]
Impaired loans and leases
Recorded Investment	126,157	121,568
Unpaid Principal Balance	151,962	145,123
Related Allowance	4,332	4,420
Residential real estate excluding Alt-A [Member] | Impaired Financing Receivable With Recorded Allowance [Member]
Impaired loans and leases
Recorded Investment	108,167	101,882
Unpaid Principal Balance	127,032	119,498
Related Allowance	4,332	4,420
Residential real estate excluding Alt-A [Member] | Impaired Financing Receivable with No Related Allowance [Member]
Impaired loans and leases
Recorded Investment	17,990	19,686
Unpaid Principal Balance	24,930	25,625
Related Allowance
Residential Alt-A [Member]
Impaired loans and leases
Recorded Investment	170,583	184,752
Unpaid Principal Balance	213,228	223,920
Related Allowance	23,000	25,000
Residential Alt-A [Member] | Impaired Financing Receivable With Recorded Allowance [Member]
Impaired loans and leases
Recorded Investment	136,995	150,396
Unpaid Principal Balance	150,849	162,978
Related Allowance	23,000	25,000
Residential Alt-A [Member] | Impaired Financing Receivable with No Related Allowance [Member]
Impaired loans and leases
Recorded Investment	33,588	34,356
Unpaid Principal Balance	62,379	60,942
Related Allowance
Home equity lines and loans [Member]
Impaired loans and leases
Recorded Investment	11,707	9,385
Unpaid Principal Balance	13,327	10,670
Related Allowance	2,986	2,306
Home equity lines and loans [Member] | Impaired Financing Receivable With Recorded Allowance [Member]
Impaired loans and leases
Recorded Investment	11,707	9,385
Unpaid Principal Balance	13,327	10,670
Related Allowance	2,986	2,306
Automobile [Member]
Impaired loans and leases
Recorded Investment	51,649	53,710
Unpaid Principal Balance	51,649	53,710
Related Allowance	15,324	11,468
Automobile [Member] | Impaired Financing Receivable With Recorded Allowance [Member]
Impaired loans and leases
Recorded Investment	51,649	53,710
Unpaid Principal Balance	51,649	53,710
Related Allowance	15,324	11,468
Other [Member]
Impaired loans and leases
Recorded Investment	10,578	8,401
Unpaid Principal Balance	10,578	8,401
Related Allowance	4,403	2,084
Other [Member] | Impaired Financing Receivable With Recorded Allowance [Member]
Impaired loans and leases
Recorded Investment	10,578	8,401
Unpaid Principal Balance	10,578	8,401
Related Allowance	$ 4,403	$ 2,084