Fair Value (Narrative) (Details) (USD $)	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011	Dec. 31, 2011	Mar. 31, 2012	Mar. 31, 2011	Dec. 31, 2010
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Discount percentage applied to real estate appraised values			15.00%
Discount percentage applied to lot development appraised values			6.00%
Book value of impaired loans	$ 169,690,000	$ 200,400,000	$ 169,690,000	$ 200,400,000	$ 187,135,000
Partial charge-offs on impaired loans			107,200,000		103,800,000
Impaired Financing Receivable, Related Allowance	10,946,000		10,946,000		15,935,000
Impaired loans carried at fair value	61,266,000		61,266,000
Book value of impaired loans carried at fair value	67,400,000		67,400,000		67,900,000
Remaining amount of impaired loans carried at cost			102,300,000		119,300,000
Impaired Financing Receivable, carried at fair value, related expense			6,800,000
MSR recorded at lower of cost or fair value	8,809,000	10,259,000	8,809,000	10,259,000	9,301,000	8,975,000	10,365,000	10,488,000
Mortgage Servicing Rights Fair Value	5,027,000		5,027,000
Valuation allowance of MSR	1,067,000	680,000	1,067,000	680,000	1,021,000	1,021,000	680,000	748,000
MSRs recorded at cost	3,800,000		3,800,000
Changes due to fair value adjustments	46,000	0	46,000	(68,000)	273,000
Other real estate owned	38,424,000		38,424,000		42,272,000
OREO devaluations	2,648,000	3,355,000	4,007,000	5,890,000	8,219,000
Commercial Receivables, excluding Commercial, Financial, and Agricultural [Domain]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Impaired Financing Receivable, Related Allowance	$ 6,153,000		$ 6,153,000		$ 10,116,000