Investments (Details 18) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Unpaid Principal Balance	$ 40,566,000	$ 61,812,000
Impaired Financing Receivable, Recorded Investment	39,956,000	60,904,000
Impaired Financing Receivable, Related Allowance	6,980,000	8,188,000
Loans And Leases Receivable Impaired At Carrying Value 1	32,976,000	52,716,000
Impaired Financing Receivable, Average Recorded Investment	49,983,000	42,589,000	41,178,000
Impaired Financing Receivable, Interest Income, Accrual Method	1,669,000	1,048,000	820,000
Commercial Real Estate Other Receivable With No Related Allowance [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Unpaid Principal Balance	13,039,000	32,088,000
Impaired Financing Receivable, Recorded Investment	12,496,000	31,496,000
Impaired Financing Receivable, Related Allowance	0	0
Loans And Leases Receivable Impaired At Carrying Value 1	12,496,000	31,496,000
Impaired Financing Receivable, Average Recorded Investment	15,549,000	14,877,000	19,253,000
Impaired Financing Receivable, Interest Income, Accrual Method	1,244,000	630,000	525,000
Commercial Real Estate Other Receivable With Related Allowance [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Unpaid Principal Balance	27,527,000	29,724,000
Impaired Financing Receivable, Recorded Investment	27,460,000	29,408,000
Impaired Financing Receivable, Related Allowance	6,980,000	8,188,000
Loans And Leases Receivable Impaired At Carrying Value 1	20,480,000	21,220,000
Impaired Financing Receivable, Average Recorded Investment	34,434,000	27,712,000	21,925,000
Impaired Financing Receivable, Interest Income, Accrual Method	$ 425,000	$ 418,000	$ 295,000