Accounting Policies - Allowance for Losses (Details) (USD $)	3 Months Ended		3 Months Ended
	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2013 Financing Loans [Member] defaulted_loan	Mar. 31, 2012 Financing Loans [Member]	Mar. 31, 2013 Collateral Dependent Not Individually Analyzed [Member]	Dec. 31, 2012 Collateral Dependent Not Individually Analyzed [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Post-Modification Recorded Investment, During the Period			$ 300,000	$ 1,100,000
Loans Receivable, Allowance, Calculation Period	3 years
Loans and Leases Receivable, Impaired, Loans Past Due Period, Minimum	90 days
Impaired Financing Receivable, Recorded Investment	127,383,000	100,351,000			68,800,000	56,000,000
Impaired Financing Receivable, Impairment analysis performed percent					54.00%	55.80%
Impaired Financing Receivable, Related Allowance	3,461,000	6,659,000			1,400,000	1,100,000
Financing Receivable, Modifications, Pre-Modification Recorded Investment, During the Period			200,000	1,000,000
Financing Receivable, Modifications, Subsequent Default, Number of Contracts			3
Financing Receivable, Modifications, Subsequent Default, Recorded Investment			$ 1,300,000