Interest Income And Interest Expense (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Interest Income And Interest Expense [Abstract]
Investment securities	$ 18,213	$ 14,161	$ 37,524	$ 26,532
Bank loans, net of unearned income	15,294	9,454	28,902	17,670
Margin balances	4,843	4,544	9,509	8,799
Other	7,763	4,734	13,004	9,698
Total interest income	46,113	32,893	88,939	62,699
Senior notes	5,163	5,164	10,327	10,341
Bank deposits	1,950	2,835	3,695	5,729
Other	1,729	4,635	3,451	7,133
Total interest expense	$ 8,842	$ 12,634	$ 17,473	$ 23,203