Fair Value Measurements, Measured On Recurring Basis Significant Unobservable Inputs (Details) (USD $) In Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
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	$ 43,767	$ 38,004	$ 47,093	$ 36,598
Purchases, sales, issuances and settlements, net		1,775		4,133
Purchases and capital calls	0		7,520
Redemptions and distributions	0		(9,975)
Brokerage and trading revenue		(11)	(576)	(80)
Gain on other assets, net	0	0	0	0
Gain on securities, net		0	18	0
Other-than-temporary impairment losses	(521)		(521)
Other comprehensive gain (loss)	412	58	99	(825)
Balance at end of period	43,658	39,826	43,658	39,826
Available-for-sale Securities [Member] | Other Debt Obligations [Member]
Fair Value Assets Measured on Recurring Basis Unobservable Reconciliation [Roll Forward]
Balance at beginning of period	5,899	17,150	6,400	17,116
Purchases, sales, issuances and settlements, net		(4,250)		(4,200)
Purchases and capital calls	0		0
Redemptions and distributions	0		(500)
Brokerage and trading revenue		0	0	0
Gain on other assets, net	0	0	0	0
Gain on securities, net		0	0	0
Other-than-temporary impairment losses	0		0
Other comprehensive gain (loss)	(6)	135	(7)	119
Balance at end of period	5,893	13,035	5,893	13,035
Other Assets [Member] | Private Equity Funds [Member]
Fair Value Assets Measured on Recurring Basis Unobservable Reconciliation [Roll Forward]
Balance at beginning of period	25,046	22,825	25,436	22,917
Purchases, sales, issuances and settlements, net		663		1
Purchases and capital calls	746		1,652
Redemptions and distributions	(783)		(2,185)
Brokerage and trading revenue		0	0	0
Gain on other assets, net	3,304	346	3,410	916
Gain on securities, net		0	0	0
Other-than-temporary impairment losses	0		0
Other comprehensive gain (loss)	0	0	0	0
Balance at end of period	28,313	23,834	28,313	23,834
Trading Securities [Member]
Fair Value Assets Measured on Recurring Basis Unobservable Reconciliation [Roll Forward]
Balance at beginning of period				9,800
Purchases, sales, issuances and settlements, net				(9,800)
Brokerage and trading revenue				0
Gain on other assets, net				0
Gain on securities, net				0
Other comprehensive gain (loss)				0
Balance at end of period		$ 0		$ 0