Accounting Policies - Allowance for Losses (Details) (USD $)	12 Months Ended
	Dec. 31, 2012 defaulted_loan	Dec. 31, 2011
Financing Receivable, Modifications [Line Items]
Loans Receivable, Allowance, Calculation Period	3 years
Loans and Leases Receivable, Impaired, Loans Past Due Period, Minimum	90 days
Impaired Financing Receivable, Recorded Investment	$ 100,351,000	$ 88,363,000
Impaired Financing Receivable, Related Allowance	6,659,000	7,296,000
Financing Loans [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Pre-Modification Recorded Investment, During the Period	2,600,000	600,000
Financing Receivable, Modifications, Post-Modification Recorded Investment, During the Period	2,800,000	600,000
Financing Receivable, Modifications, Subsequent Default, Number of Contracts	1
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	200,000
Financing Receivables, Impaired, Troubled Debt Restructuring, Write-down	(300,000)	(100,000)
Collateral Dependent Not Individually Analyzed [Member]
Financing Receivable, Modifications [Line Items]
Impaired Financing Receivable, Recorded Investment	56,000,000	42,000,000
Impaired Financing Receivable, Impairment analysis performed percent	55.80%	47.60%
Impaired Financing Receivable, Related Allowance	$ 1,100,000	$ 900,000