Loans and Allowance for Loan Losses - Recorded investment in nonaccrual loans by loan class (Details 6) (Loans Receivable, USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012	Jun. 30, 2012
Recorded investment in nonaccrual loans by loan class
Nonaccrual Loans	$ 27,864	$ 109,894	$ 115,340
Balance as a percentage of unpaid principal	62.60%	69.50%	68.80%
Commercial (secured by real estate)
Recorded investment in nonaccrual loans by loan class
Nonaccrual Loans	7,237	22,148	19,115
Commercial & industrial
Recorded investment in nonaccrual loans by loan class
Nonaccrual Loans	548	31,817	34,982
Commercial construction
Recorded investment in nonaccrual loans by loan class
Nonaccrual Loans	504	23,843	18,175
Commercial
Recorded investment in nonaccrual loans by loan class
Nonaccrual Loans	8,289	77,808	72,272
Residential mortgage
Recorded investment in nonaccrual loans by loan class
Nonaccrual Loans	14,338	12,589	16,631
Residential construction
Recorded investment in nonaccrual loans by loan class
Nonaccrual Loans	4,838	18,702	25,530
Consumer installment
Recorded investment in nonaccrual loans by loan class
Nonaccrual Loans	$ 399	$ 795	$ 907