Fair Value (Narrative) (Details) (USD $)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011	Jun. 30, 2012	Jun. 30, 2011	Dec. 31, 2010
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Impaired Financing Receivable, Carrying Value	$ 142,300,000		$ 142,300,000		$ 187,100,000
Discount percentage applied to real estate appraised values			15.00%
Discount percentage applied to lot development appraised values			6.00%
Partial charge-offs on impaired loans			117,500,000		103,800,000
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	7,579,000		7,579,000		15,935,000
Impaired Financing Receivable, Related Allowance	7,579,000		7,579,000		15,935,000
Impaired loans carried at fair value	56,405,000		56,405,000		67,900,000
Partial Charge-Offs On Impaired Loans carried at Fair Value			91,500,000		97,600,000
Book value of impaired loans carried at fair value	62,000,000		62,000,000		78,000,000
Remaining amount of impaired loans carried at cost			80,300,000		109,100,000
Impaired Financing Receivable, carried at fair value, related expense	5,200,000		10,700,000
MSR recorded at lower of cost or fair value	8,346,000	10,069,000	8,346,000	10,069,000	9,301,000	8,809,000	10,259,000	10,488,000
Mortgage Servicing Rights Fair Value	6,100,000		6,100,000
Valuation allowance of MSR	1,611,000	680,000	1,611,000	680,000	1,021,000	1,067,000	680,000	748,000
MSRs recorded at cost	2,200,000		2,200,000
Changes due to fair value adjustments	544,000	0	590,000	(68,000)	273,000
Other Real Estate, Foreclosed Assets, and Repossessed Assets, Fair Value	33,500,000		33,500,000		42,272,000
OREO devaluations	425,000	588,000	4,432,000	6,478,000	8,200,000
Commercial Receivables, excluding Commercial, Financial, and Agricultural [Domain]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Impaired Financing Receivable, Related Allowance	$ 5,575,000		$ 5,575,000		$ 10,116,000