Fair Value Measurements, Measured On Recurring Basis Significant Unobservable Inputs (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Available-for-sale Securities [Member] | Municipal and Other Tax-exempt Securities [Member]
Fair Value Assets Measured on Recurring Basis Unobservable Reconciliation [Roll Forward]
Balance at beginning of period	$ 40,702	$ 42,353
Purchases and capital calls	0	0
Redemptions And Distributions	(98)	(100)
Gain (loss) recognized in earnings [Abstract]
Gain on other assets, net	0	0
Gain on available for sale securities net	0	1
Other-than-temporary impairment losses	0	0
Other comprehensive gain (loss)	(1,597)	(277)
Balance at end of period	39,007	41,977
Available-for-sale Securities [Member] | Other Debt Securities [Member]
Fair Value Assets Measured on Recurring Basis Unobservable Reconciliation [Roll Forward]
Balance at beginning of period	5,399	5,900
Purchases and capital calls	0	0
Redemptions And Distributions	0	0
Gain (loss) recognized in earnings [Abstract]
Gain on other assets, net	0	0
Gain on available for sale securities net	0	0
Other-than-temporary impairment losses	0	0
Other comprehensive gain (loss)	(206)	0
Balance at end of period	5,193	5,900
Available-for-sale Securities [Member] | Equity Securities and Mutual Funds [Member]
Fair Value Assets Measured on Recurring Basis Unobservable Reconciliation [Roll Forward]
Balance at beginning of period	2,161
Purchases and capital calls	0
Redemptions And Distributions	0
Gain (loss) recognized in earnings [Abstract]
Gain on other assets, net	0
Gain on available for sale securities net	0
Other-than-temporary impairment losses	0
Other comprehensive gain (loss)	311
Balance at end of period	2,472
Other Assets [Member] | Private Equity Funds [Member]
Fair Value Assets Measured on Recurring Basis Unobservable Reconciliation [Roll Forward]
Balance at beginning of period	28,169	30,902
Purchases and capital calls	492	1,089
Redemptions And Distributions	(830)	(607)
Gain (loss) recognized in earnings [Abstract]
Gain on other assets, net	1,385	(391)
Gain on available for sale securities net	0	0
Other-than-temporary impairment losses	0	0
Other comprehensive gain (loss)	0	0
Balance at end of period	$ 29,216	$ 30,993